During filming Kyle Gallner suffered a panic attack whilst being tied to a cross, which the crew were unaware of at first, thinking he was still acting.

The Westboro Baptist Church planned to protest Red State at its premier at the Sundance Film Festival. Kevin Smith in turn planned a counter protest which he and his fans took part in. At the premiere the counter-protesters heavily outweighed the handful of Westboro protesters who showed up. This occurred 12 years after Smith's first film to tackle religious controversy, Dogma (1999), drew protests from certain sects of the Catholic Church, one of which Smith jokingly took part in himself.

There is no score for this film. The entire soundtrack consists of songs sung within the film itself.

The whole film was shot in sequence.

Shot over a period of 25 days, using the all-digital Red camera system, director and editor Kevin Smith could edit the footage the day he shot it. Because of this between shooting scenes Smith would be editing almost non-stop. As a result, a mere 2 days after the last shot was done, Smith was able to show a fine-cut of the film to the entire cast and crew at the wrap party.

After a screening of the film in Kansas City, Kevin Smith interviewed two life long Westboro Baptist Church members (Shirley Phelps niece and son) who had defected a few years prior. They both enjoyed the film and even complimented Smith on how realistic certain aspects of religious fanaticism are depicted.

Little did Kevin Smith know Michael Parks was actually a country singer early in his career who sang with the likes of Johnny Cash. Many of the country-gospel songs sung in the film were suggested by Parks during filming. Later after the film was completed Parks re-recorded the songs onto an album.

A first for writer/director Kevin Smith, he has stated this film is a strict non-comedy saying, "It's a nasty-ass $4mil horror flick with few (if any) redeeming characters."

At the premier of the film at the Sundance film festival, Kevin Smith said he would "pick the distributor 'auction style'" immediately following the screening. After the screening he then pulled producer John Gordon on stage to conduct the auction. Smith then bid $20 for distribution rights and Gordon immediately sold it to him. Smith revealed it was his plan all along to self-distribute the film himself.

Kevin Smith wrote the role of Abin Cooper for Michael Parks after seeing his performance in From Dusk Till Dawn (1996). Smith has said that if Parks had not agreed to be in the film, he would have dropped the project entirely.

Released on tour in March 2011, Kevin Smith invited the WBC and specifically Megan Phelps-Roper over Twitter to attend the Kansas City screening and Q&A. Megan and around 15 other members of WBC attended the screening and some brought their young children along. Smith warned the family that the film's content was for a mature audience and not suitable for children, but was promptly told off by the church members. Less than 20 minutes into the screening, the entire WBC audience attending the event walked out, outraged by the film's content. Megan called the film "filth" and "a vulgar piece of tacky melodrama."

This is one of Quentin Tarantino's favourite films of 2011.

The budget for the special effects department was $5000.

Samuel L. Jackson was considered for the role that eventually went to John Goodman.

The megaphone John Goodman uses when announcing his team's arrival is actually from Kevin Smith's home where he would use it to communicate with his pets and family. Smith thought that it looked professional enough and that Goodman's character might pick it up on the way as "a sort of last minute, oh 'sh--t' sorta thing."

Kevin Smith wrote the script around the same time he was writing Zack and Miri Make a Porno (2008) and presented them both to the Weinstein brothers. They immediately gave the green light to Zack and Miri Make a Porno, but declined on Red State fearing its story was too bleak to attract an audience. Had they green lit, Red State would've been shot back to back with Zack and Miri.

Kevin Smith's lowest budget film since Chasing Amy (1997).

Casting director Deborah Aquila was moved to tears whilst listening to Kyle Gallner's performance during the cage scene.

Alan Rickman was considered for the role played by John Goodman, but Alan was busy filming Harry Potter

Kevin Smith had originally wanted to shoot the film on location in a real Red State around middle America. However, due to budget constraints he ended up shooting it all just outside Los Angeles.

This is the first feature Kevin Smith and his cinematographer David Klein shot using the all-digital Red camera.

Kevin Smith stated on his podcast Hollywood Babble-On 55 that the name Abin Cooper comes from the Green Lantern character Abin Sur and a character from indie film The Reflecting Skin (1990).

Canon 7D's were used as B-cameras.

Kevin Smith was gifted a poster by one of the many protesters for the film that was the theatrical poster with the word "Fags" added to the title. One night, Smith took his wife and daughter out to dinner while maids were cleaning their house. When they returned home, they found that the maids had displayed the poster right in the living room, so it was staring at them when they entered. Smith and his wife were horrified that their daughter had seen the poster, but she simply assumed it was for a sequel and thought nothing of it.

The first draft of the script was dated 9/5/07.

Director Kevin Smith's wife Jennifer Schwalbach Smith played Esther, a believer

Melissa Leo and John Goodman also co-stared in the HBO series 'Treme'

Kevin Smith: Smith has a quick off-camera cameo at the end of the film, as a prison inmate, yelling the last line in the film.

In one of his Q&As, Kevin Smith revealed that the original ending to the film featured the Apocalypse: after Cooper taunts Keenan, he and the other members of the church along with every agent, save Keenan, dies with their hearts and heads exploding. After hiding during the violence, Keenan uncovers his eyes to see the last church member being killed by a gigantic angel, who sees Keenan and simply puts its fingers to its lips and goes "Shhhhh..." before ascending to Heaven as the Four Horsemen of the Apocalypse descend onto Earth.

During filming Nicholas Braun suffered a concussion; when the CO2 squib fired, he fell back and the pressure from the squib knocked a box off a shelf and onto his head. According to Kevin Smith, when he showed up at the emergency room escorting Braun, the actor was still wearing a prosthetic gunshot wound on his forehead, sending the E.R. staff into a frenzy.

Due to the limited budget, a number of the smaller characters were played by family members and friends of cast and crew. One of the youngest believers was played by Ivy Klein, daughter of the film's cinematographer David Klein. Ivy was carefully prepped for the scene in which Cheyenne ('Kerry Bishe') tells the three young girls to go hide in the attic. However when it came time to shoot the scene, Ivy actually got scared and started screaming, which was not in the script. Smith got her parents' approval to use the footage in the movie. Smith felt terrible for scaring Ivy, and offered her father some money to take Ivy to a toy store. Her father replied, "Add it to the pile", as other cast/crew members had felt the same. According to Smith, the next time that Ivy saw Kerry was two days later at the Craft Services area. Ivy got a scared look on her face and said, "You're not going to act again are you?"

In the sequence outside the compound when Agent Keenan (John Goodman) yells at Sheriff Wynan (Stephen Root) to go back into his car, Root's subsequent stumble and fall was unscripted. Root admitted that he was genuinely startled by Goodman's performance, and was happy to have Smith keep the footage in the film.

Smith originally planned to have the first "prisoner" executed with a goat's head on top of his own. The special effects director told him that he might be thinking of a ram's head, because a goat is actually very small. Smith found out shortly thereafter that the ram's head would cost $5,000 - his entire special effects budget - and scrapped the entire idea. He came up with the plastic wrap and top-down shot because he thought it would contain the most "blood" and therefore not require much cleanup between takes.

Smith has said that there are ten "Easter Eggs" (hidden jokes or surprises) in the film. He plans to only discuss each one as they are discovered by fans. The first is that Sheriff Wynan "enters and exits the film with a shot to the face."

The sound effect used for the horn heralding the arrival of the apocalypse was also used in the 2010 film Legion to herald the arrival of the archangel Gabriel, bringing with him the apocalypse.