Lizzy Caplan (Marlena) did not know what she was auditioning for. She thought it was a romantic movie until her second audition, where she read a scene from Alias (2001). It wasn't until after she was offered the role that she found out it was a monster movie, and the actors weren't allowed to read the script until after they signed on.

The running time of the film, without credits, is about 80 minutes, the length of a long-running MiniDV tape, a common format used in consumer camcorders.

The first trailer for this movie played before Transformers (2007). It showed a giant explosion in the heart of New York City and the Statue of Liberty's head being thrown down a street. It was shot with a hand-held video recorder. There was no title.

According to Neville Page, creature designer - the monster is a baby in a new environment - "spooked" and looking for its mother.

During the first weekend of the release, many theaters posted signs warning guests that the hand held camera movements may cause motion sickness.

The head of the Statue of Liberty is shown about 50% larger than actual size. CG supervisor David Vickery said in an interview that many people imagined the head being much bigger than it actually is, and that the size was increased due to complaints that the head looked too small in the trailer.

The DHARMA Initiative logo, a fictional research project featured in the television series Lost, can be seen briefly at the start of the film.

In the teaser trailer, the voice yelling "I saw it! It's alive! It's huge!" is that of Director Matt Reeves.

The decapitated head of the Statue of Liberty in the street is inspired by the poster for John Carpenter's Escape from New York (1981), which depicts the head of the Statue of Liberty lying in the middle of the street.

All the main characters (and Jamie) have MySpace pages. The producers made these pages to advertise on MySpace. All the characters last logged into them on January 18, 2008. (1-18-08), the release date of the film.

The film has no music score and music for the end credits does not begin until 1 minute and 30 seconds after the credits start rolling.

The title "Cloverfield"; initially just a codename for the movie, is named for the boulevard in Santa Monica, California where the Bad Robot production offices were located during the making of the film.

Some footage in the film was shot by the actors.

The film was shot in 34 days, in Los Angeles under the fake title "Slusho" and in New York under the fake title "Cheese". The Ferris wheel scene, the last in sequential order, was filmed on the first day. The scene inside Beth's parents' apartment, the first in sequential order, was filmed on the last day.

Images from King Kong (1933), The Beast from 20,000 Fathoms (1953), and Them! (1954) are hidden within the film. Each image is seen extremely briefly, for only a single frame, during a camera edit. The "Them!" picture is shown at 00.24.06, the "Beast from 20,000 Fathoms" picture is shown at 00.45.27, and the "King Kong" picture is shown at 1.06.55. A brief clip of Rob and Beth at a train station is seen with the "King Kong" image at 1.06.51.

One of the original ideas for a title for the movie was "Greyshot," both a reference to the hand-held style of filming and the name of the bridge in Central Park where Rob and Beth take refuge.

The voice yelling "Oh my God!" repeatedly when the head of the Statue of Liberty lands on the street is producer Bryan Burk.

Eric Leven - the visual effects supervisor - refers to the monster as "Clover".

At the beginning of the film there is a textual reference to DARPA - The Defense Advanced Research Projects Agency which is an agency of the United States Department of Defense responsible for the development of new technology for use by the military.

The only "score" composition for this film is an instrumental piece by Michael Giacchino played over the end credits, titled "Roar! (Cloverfield Overture)". This composition was intended to evoke the score of classic monster movies of the '50s and '60s (e.g. Godzilla). Roar! was not included on the soundtrack CD (which was packaged as a mix CD of music from Rob's surprise party), and as of 2011 has not been officially released on CD, but it was included when the soundtrack collection was later released on iTunes.

The voice in the mysterious radio broadcast that plays after the end credits is director Matt Reeves.

When the teaser trailer with the head of the Statue of Liberty was shown without a film title, but a reference to J.J. Abrams, many Abrams fans looked to the internet to find out as much as possible about the upcoming, mysterious film. Abrams launched a viral campaign using multiple internet websites to promote this film, each providing background details of the plot. However, given the mysterious nature of the film and the viral websites, a number of theories were promoted on the blogosphere that were eventually proven untrue; for example, one hypothesis involved three Biblical monsters, one each for the sea, the land, and the air, instead of the single monster that came onto land from the depths of the sea.

The opening party scenes were filmed without music, and the guests in the background were silently pretending to talk to one another. All the music was added in post-production.

One of the promotional websites, Jamieandteddy.com (password "jllovesth"), shows videologs (vlogs) made by the title couple about their relationship (which turns sour). Jamie Lascano is only seen at the party unceremoniously unconscious on the couch, and Teddy Hanssen is nowhere to be found (although on 1-18-08.com, he is now identified as "missing"). The actors who play either of the two are not confirmed. Though it has been speculated that Jamie is played by Blake Lively, this is incorrect.

Jason (Mike Vogel) can be seen wearing a Slusho! T-shirt throughout the movie. Slusho! is a drink from J.J. Abrams' show Alias (2001) as well as a codename of the film's, and the shirt is the only time the beverage is acknowledged during the movie, with far more information hinted about it on the Internet.

About 104 recorded people left the theater suffering from dizziness and motion sickness.

According to Annie Pomeranz - visual effects producer - puppets were used in the scene involving the "parasites" inside the tunnel but the scene turned out to be more interactive than originally thought and CGI animation was required. However, Matt Reeves - the director - states that the scenes with the puppets were too "goofy".

The teaser trailer, as was planned, was shot before principal production began with digital cameras.

Film debut for T.J. Miller.

The monster was designed by artist Neville Page. He sought a biological rationale for the creature, though many of his ideas would not show up on screen. Page designed the creature as immature and suffering from "separation anxiety". He compared the creature to a rampaging elephant, saying "there's nothing scarier than something huge that's spooked". Page said of the creature's backstory, "For me, one of the most key moments in our collective brainstorming was the choice to make the creature be something that we would empathize with. It is not out there just killing. It is confused, lost, scared. It's a newborn. Having this be a story point (one that the audience does not know), it allowed for some purposeful choices about its anatomy, movement and, yes, motivations". The creature was developed by visual effects supervisor Kevin Blank and Phil Tippett's company Tippett Studio. Blank described the intended goal of the creature, "Rather than the monster having a personality [like Godzilla or King Kong], it's more of an entity or an event". Reeves described the creature's reaction to its surroundings thus: "It's this new environment that it finds frightening". To indicate this, Reeves suggested the addition of white in the creature's eyes so it would look similar to a spooked horse. The filmmakers generated and used the idea of parasites because the film could not realistically have scenes between the human protagonists and the enormous creature.

The movie is viewed primarily from the point of view of Hudson "Hud" Platt, the character who uses the camera the most. H.U.D. is also short for "Heads-Up Display", a method for overlaying information onto a view of one's surroundings such as Timestamps on video footage.

Prints were shipped to some theaters under the name "Bertha".

It is revealed in the Cloverfield Blu-Ray Notations that Travis (Beth's date) left Manhattan Island (via his car) before the events of the movie began. He left via the Lincoln Tunnel and went to his home in Weehawken. He was at home through the duration of the attack.

The creature Hud mentions being discovered in Madagascar is the coelacanth, an order of fish known from the fossil record and thought to have been extinct since the end of the Cretaceous era (about 70 million years ago), a classic example of what is known as a "Lazarus taxon", a species thought to have been extinct but found to still be alive. The first modern coelacanth was actually discovered off the eastern coast of South Africa (not Madagascar). Today, coelacanths are found in Madagascan waters as well. Some think that the creature Hud mentions might have been the megamouth shark; however, megamouth sharks were not known to science at all and, thus, not thought to have been extinct before being discovered. The first specimen of the megamouth shark was discovered near Hawaii, the other side of the world from Madagascar.

During the trailer, some falling, fiery debris hits the top of a building revealing the words, "ACE 1987-2004", on a dark wall. This is mainly an easter egg relating to the ACE awards.

J.J. Abrams has used the number 47 extensively on past projects. In Alias (2001) it played great importance as a page on Rambaldi's manuscript, and as a recurring pointer to important motifs. It should come as no surprise that "Cloverfield" is the designation to the case of the images found on Area US-447. Also, in the scenes where they're taking the stairs up to the top of the skyscrapers to save Beth, one of the floor numbers filmed is the 47th.

Jamie, in her brief appearance passed out on the couch at the party, is wearing the same outfit she wore in her video #11 on jamieandteddy.com. In the video she mentions "this thing" Lily put together and that she's going to it (evidently the party).

To prevent the leaking of plot information, instead of auditioning the actors with scenes from the film, scripts from Abrams' previous productions were used, such as the television series Alias and Lost. Some scenes were also written specifically for the audition process, not intended for use in the film. Despite not being told the premise of the film, Lizzy Caplan (Marlena) stated that she accepted a role in Cloverfield solely because she was a fan of the Abrams-produced Lost (in which her former Related co-star Kiele Sanchez was a recurring character), and her experience of discovering its true nature initially caused her to state that she would not sign on for a film in the future "without knowing full well what it is". She indicated that her character was a sarcastic outsider, and that her role was "physically demanding".

Visual main effects supervisor Nick Tom and Phil Tippett's "Tippett Studio" were enlisted to develop the visual effects for Cloverfield. Because the visual effects were incorporated after filming, cast members were only familiar with early conceptual renderings of the beast and had to react to an unseen creature during their scenes. Artist Neville Page designed the monster, creating a biological rationale for it, though many of his ideas, including an "elongated, articulated external esophagus," would not show up on screen. His central concept was that of an immature creature suffering from "separation anxiety." This recalls real-life circus elephants who get frightened and lash out. The director stated that "there's nothing scarier than something huge that's spooked."

Many scenes were shot with the Panasonic HVX200 "prosumer" digital video camera. Visual effects plates were shot primarily with the Thomson Grass Valley Viper Filmstream digital video camera; the effects camera in NYC was the Sony F23 digital video camera.

The man they encounter in the alley who speaks to Hud is speaking Ukrainian he was saying in Ukrainian, to help find his daughter and his family as he can't live without them.

It was initially speculated by fans that Rob knew more about the mysterious situation than he was letting on to anyone, due to his reaction (in the teaser trailer), that of being uncomfortable rather than terrified.

Matt Reeves added that "The parasites have a voracious, rabid, bounding nature, but they also have a crab-like crawl. They have the viciousness of a dog, but with the ability to climb walls and stick to objects."

The San Jose Mercury News described the creature as "a monster for the MySpace generation". Reviewer James Berardinelli noted, "The movie follows the Jaws rule that monsters are usually more intimidating when they are shown infrequently and only in brief glimpses". Amy Biancolli of the Houston Chronicle described the creature as retaining "an air of mystery-a monstrous je ne sais quoi that makes him all the freakier." Richard Corliss of Time complained of the recycled elements of the creature, such as its emergence mimicking the original Godzilla film and its parasites being similar to the "toy meanies" from Gremlins (1984).

Neville Page, in response to claims that the design of the creature was similar to that of the South Korean film The Host (2006) said, "They are [similar] in that they ravage and seem to originate from the water, but the end results are quite different. However, when I finally saw some of the concept art, there were some very obvious similarities. But then again, I think that we were both channeling similar biological possibilities."

One defense of the absence of children and the elderly in the film is that they're less likely to be out after midnight when the monster attack begins. The filmmakers would also have had several practical concerns with regarding using children, as (1) child labor laws prevent filmmakers from using child models at night, (2) children are more likely to disclose guarded information to the public, (3) children require added efforts to keep them safe, (4) underage models require an additional signature on the release form which creates delays and coordination problems, (5) the American public is very sensitive about the depiction of children being harmed. Children and the elderly are not entirely banished from the film: one old man can be seen when the Statue of Liberty's head lands in the street. The crying of a baby can be heard in one stairwell scene early in the film.

Many fans think that the digital recreation of the head of the statue of liberty is to small which is untrue, the movie shows us the actual proportions of the Statue of Liberty. These dimensions are taken from the National Park Service: (1) Head from chin to cranium, 17 feet 3 inches (5.26 metres); and (2) Head thickness from ear to ear, 10 feet 0 inches (3.05 metres). The head could easily fit on a city street, even on its side. The whole statue is only 151 feet (46.02 metres) high. The pedestal adds another 154 feet (46.94 metres). The makers of the film cited Escape from New York's poster as the inspiration for the Statue head scene in Cloverfield. However, that film's poster depicts the head as unrealistically large, which might account for the misconception that the head in Cloverfield is too small. There had also been claims that the head is too big. Supposedly, the creators received many complaints of the head looking too small in the teaser trailer, so they increased the head's size by 50% for the movie. If you compare the head in the teaser trailer with the head in the theatrical trailer, it appears larger in the latter.

In the beginning of the movie, Beth, played by Odette Yustman, talks about the footage Rob was filming "ending up on the Internet". Yustman also starred in a movie called Reckless Behavior: Caught on Tape (2007), in which she plays a teacher whose career is ruined when a video of her winds up on the Internet.

Both Jessica Lucas and Odette Annable starred in DC television shows on Fox and the CW channel Jessica Lucas in Gotham (2014) as Tabitha Galavan, and Odette Annabel as Reign on the CW show Supergirl (2015) and T.J. Miller starred in the Marvel movie Deadpool (2016) and its sequel Deadpool 2 (2018) as Deadpools sidekick Weasel.

It is unclear what causes marlena to die from the parasite bite, at first, she just feels dizzy. Then she starts to bleed from her eyes and ears, so the military personnel take her behind a curtain while shouting, "We've got a bite!" Watch closely and you'll see her stomach expand and burst blood all over the wall. Why this happens is unknown. Some possibilities that viewers have suggested include (1) something in the monster's saliva causes her body to create an excess of fluid or gas, (2) the bite from the parasites injects some sort of anticoagulant that breaks down the blood, causing it to ooze from her eyes and ears and to accumulate in her stomach, and (3) the small monsters reproduce by biting their prey and impregnating them (somewhat like the Alien movies. Note that as she's being taken away by two medics, a rifle is trained on her stomach). Marlena's death is actually foreshadowed when they exit the subway and get escorted to the infirmary. In one brief shot, a dead soldier, whose chest and stomach had burst open, is wheeled past on a stretcher and one soldier in a blue haz-mat suit explaining "another bite victim". Even earlier, when the monster first attacks, we hear a woman screaming in one of the ambulances. This is followed by some unusual noises. Her scream is loud and piercing. Later, Marlena makes the same horrible scream

Beth's dad's apartment is a real building though it's not strictly an apartment complex. The building is the Time Warner Center, located at Columbus Circle on the southwest corner of Central Park. There are two towers, containing offices and residences, connected to one base which contains a shopping center. It was completed in 2003.

What accounts for the monsters gigantic size is the phenomenon deep-sea gigantism. The term means that some creatures, who are relatively small when conceived near to the surface, get progressively larger as they develop deeper and deeper in the ocean. For example, squid are usually a maximum of 60 cm in length, but the Giant Squid, which can reside at depths of over 900 m, can reach up to 13 m in length. As for what kind of creature grew to that size, the monster does somewhat resemble animals in the amphipod order. It could be posited that the monster was disturbed by the oil drilling rig and then followed a tanker ship to the New York harbor (the first thing it destroyed was a tanker ship), where it then proceeded to rip apart the city, finding it a threat. The little creatures that attached themselves to it could be ectoparasites that live on the monster. One might imagine that the monster's strength, and the toughness of its skin, might be some sort of adaptation to the extremely high pressures of the deep ocean. But this would be wrong, because real-life deep sea organisms do not require such features to survive. As discussed here, it is differences in pressure that are dangerous to organisms, so they will experience no significant problems as long as the liquid in their body is at equally high pressure as the surrounding water, and as long as they have no gas-filled body cavities at lower pressure like humans do. The MarineBio Conservation Society's article "The Deep Sea" states (in the "Pressure" subsection), With good samples, we now know that deep sea creatures have adapted to pressure by developing bodies with no excess cavities, such as swim bladders, that would collapse under intense pressure. The flesh and bones of deep sea marine creatures are soft and flabby, which also helps them withstand the pressure. As for respiration, while it is unlikely that the monster could breathe the air if it really was a deep-sea organism, the deep ocean is a low-oxygen zone, meaning the monster would have had to develop ways to absorb and process what oxygen it had available, as well as store it for long stretches of time. Sites such as 1-18-08.com describe(d) a secret ingredient for a drink named Slusho. This ingredient named Seabed Nectar is found deep underwater under awesome pressure and in freezing temperatures. It is possible that this chemical mutated a deep sea animal and created the monster or that the chemical came from the monster itself.

The first building we see collapse is the Woolworth Building, located in Downtown Manhattan on Broadway. We see the building while facing directly down Broadway towards the Battery. We don't see anything done to it directly. Its old age, and sunken-caisson foundation, may partly account for its collapse. The Woolworth Building (standing at 792 feet) was the tallest building in the world when it was finished in 1913 and, outside the world of Cloverfield, is still among the tallest buildings in Manhattan. Some reviewers incorrectly identified the Woolworth Building as either the Empire State Building or the Chrysler Building. We never see any damage done to either of them.

Confirmed to be getting a direct sequel on April 26, 2018

In the manga series, we learn the monster attacked Japan it attacked Manhattan.. and when the film was released on DVD in Australia, videos of the monster attacking Sydney and Melbourne appeared.

Actress Odette Annabel plays a character named Beth McIntyre. In the film Black Swan, Winona Ryder plays a character named Beth McIntyre, a woman who once played the role of Odette in Swan Lake.

Jessica Lucas would later star in another disaster movie Pompeii (2012).

Despite controversy from fans about there being 2 giant monster's is completely false because differences in the main monster's appearance, such as color and size, can be explained by lighting and camera angles. In the film, the military refer to just one: "Whatever it is, it's winning." The filmmakers have consistently referred to it as "the monster" rather than "monsters." Director Matt Reeves has confirmed that the way the creature is filmed merely creates the illusion that there are differences in size.

Just like her character that she portrays Jessica Lucas is Canadian and has the astrological sign Libra.

Hud is interested in comic books and may work as an intern in that industry. He has invited friends on the MySpace community to submit pictures of their original comic book characters, and intends to interactively develop a story, also worth noting and coincidentally T.J. Miller starred in the Marvel comic book movie Deadpool (2016) and its sequel Deadpool 2 (2018) as Weasel the sidekick to Deadpool.

T.J. Miller (Hud) and Ben Feldman (Travis) starred together in the HBO show Silicon Valley (2014).

Beth dislikes Madden Football and feels that the men she knows spend too much time playing it, but enjoys surfing and lateral riddles.

Both T.J. Miller (Hud) and Theo Rossi (Antonio) share the same birthday, June 4th.

Both Mike Vogel and Odette Annable are left handed.

Although Hud was filming most of the movie, the camera was actually Rob's camera. It was handled by Rob first on April 27th, and later by Jason and Hud on May 22, the day of Rob's farewell party.

Chris Mulkey has a small role in the film as military officer Lt. Col. Graff. 26 years earlier Chris Mulkey starred in First Blood (1982) as Deputy Ward.

The Department of Defense names the creature "LSA" for Large-Scale Aggressor in the film's Blu-ray special feature called "Cloverfield Special Investigation Mode".

The very first scene in the film (Rob in Beth's apartment), was actually the last scene to be shot.

Laetitia Casta: Model in the poster inside the Sephora shop exterior where Lily, Marlena, Rob and Hud stop after running from the Brooklyn Bridge, before Rob enters the electronics store.

In the final scene where a few seconds of the original taped-over footage of Rob & Beth in the Coney Island Ferris Wheel is shown, the camera, looking out to sea, appears to inadvertently catch the unidentified falling debris that was carrying the monster

After viewing a cut of the film, Steven Spielberg suggested giving the audience a hint at the fate of the monster during the climax. This resulted in the addition of the broadcast overheard on the military helicopter's radio, as well as the sounding of air raid sirens, both to signal the forthcoming "Hammerdown" bombing mentioned earlier in the film.

After the closing credits there is a mysterious broadcast voice. When played in reverse, the broadcast says, "It's Still Alive."

It was originally intended for the Brooklyn Bridge to be destroyed by one of the monster's hands, but it was decided that this seemed too deliberate. It was changed to the monster's tail destroying the bridge, which seemed more accidental.

Hud was originally going to survive, but producer J.J. Abrams suggested having him being eaten by the monster, allowing the audience a somewhat vicarious experience. The scene was then planned as having Hud being eaten instantly after turning around, but it was decided that the audience deserved a good look at the monster, which resulted in the longer shot with the monster leaning down to inspect Hud before biting and killing him.

Producer J.J. Abrams came up with the film's last line, "I had a good day."

While all the other main characters in the film die, it is unknown what happens to Lily It is widely believed though that a flaming object that comes rolling into the view of Rob's Camera is Lily's helicopter, but a "Special Effects" featurette on the Cloverfield DVD reveals it is a truck (or military vehicle),one thing that suggests she might have died is that Lily has not logged back into her MySpace account. She has this in common with Hud and Marlena, who both unquestionably died, and Rob and Beth, who probably died. (Note that the real-life MySpace accounts for fictional characters are part of a marketing campaign; and no one is obligated to take publicity into account.) The survival of Lily has at least two arguments in its favor. Or rather, her survival has one argument in its favor and one common argument against it proven wrong. First, Rob lists the persons he saw killed by the monster--Marlena, Jason and Hud. He doesn't mention Lily, which at least suggests that he believes she's alive.

Near the end of the film (at around 1 hr 13 mins) when they are at the fair you see something drop from the sky in the right-hand side.

According to Director Matt Reeves in the DVD documentary, the last shot of the film, when Rob and Beth are on Coney Island, was the very first shoot of principal photography, while the very first scene in Beth's dad's apartment was the very last shoot of principal photography.

Although it wasn't stated by anyone that worked on Cloverfield, there are some who believe Jason might've lived, though the film suggests otherwise. In a DVD special feature for the film, Mike Vogel jokingly comments that Jason could've survived since you didn't see him perish.

On Hud's Myspace page his height went from 6ft2 to 2ft6 (due to being bitten in half by the monster).

Some fans wondered why the helicopter pilot didn't alter his flight path away from the monster when they were bombing the monster, there are several possible reasons why the pilot did not alter his flight path (1) the pilot didn't notice the monsters direction or travel, (2) the pilot didn't believe the monster could threaten the crew at that altitude (3) the altitude of the chopper was only barely above the highest Manhattan rooftops at that point, and it may have still been trying to gain altitude before changing direction, (4) the pilot may have been given orders to evacuate via a fixed route, and the pilot may have been reluctant to disobey his orders, (5) the pilot may have been instructed to stay on his current flight path in order to avoid the risk of being hit by the bombs falling near him from the B-2 bombers above them, but the most likely explanation is that the monster may have paralleled the helicopters flight path by accident.

The buildings and landmarks in New York that are either damaged or destroyed throughout the course of the film include the Statue of Liberty, Woolworth Building, Brooklyn Bridge, Time Warner Center, Grand Central Terminal and the Solow Building

There is static at the end of the credits and then a voice says "It's still alive" backwards. You have to play it backwards to hear it correctly.

Despite not being viewed clearly or properly, Hud was really bitten in half by the monster because if you view it carefully as the monster chews on him, there is about one second where we can see Huds legs sticking out between the monsters teeth, right before the monster bites down hard and Huds top half goes spinning towards the ground. As he falls out of the monsters mouth, we can see his legs above him still sticking out of the teeth, as the camera falls to the ground, we can see Hud's left-hand flailing about in front of the camera and we can see his face. When the top half of Huds body lands on the ground, the camera is showing only his head (right profile shot) and shoulders. If you slow down the movie frame by frame you can see his shadow on the ground, and it is that of an upper torso.

The scene when Hud looks directly at the monster (before getting killed), was not planned. J.J Abrams came up with the idea during the filming of the helicopter crash.

Marlena said she saw the monster eating people; which foreshadows the fate of Hud at the end when he gets bitten in half by the monster.

When Marlena is first introduced, the Blood Arm song "Do I have your Attention?" is playing on the stereo at the party. In addition to providing a running commentary on Hud's attempts to pick up Marlena ("Oh, I'll try it again, despite all your rejection"), one of the song's lines, audible when the camera is zoomed in on Marlena's head and shoulders, is "Nobody notices 'til someone explodes." Marlena later explodes after being bitten by one of the parasites.

Some fans think that the hidden voice at the end ("Help us! "It's still alive") was Rob, however this is untrue and the hidden message isn't really true because J.J. Abrams said the bombing killed the monster.

Beth suffers from a substantial injury to the side of her chest from a rebar when being rescued from her building but is able to walk and run without suffering from any pain is due to all the adrenaline and excitement in her body giving her almost superhuman endurance.

They filmed two possible death scenes for Marlena. The one that we see in the film and one where her death took slightly longer.