Seth Rogen originally wrote the part of Saul Silver for himself to play. It wasn't until the table read that he realized James Franco would be funnier in the role of Saul.
James Franco's line "It smells like God's vagina" was actually originally improvised by Seth Rogen. James Franco told him it wasn't funny, then used the line in the next take.
The diner scene near the end of the film was not in the script. It was improvised on the spot by the actors.
The fight scene between Saul (James Franco) and Carol (Rosie Perez) was, for the most part, improvised. Because of this, Franco was worried that he would hurt Perez, and would ask her for permission to do certain things during the fight. In the end, Perez actually did get hurt, and got a bruise after Franco accidentally bit her too hard on the thigh, but Perez didn't tell him until after filming was done, so he wouldn't feel bad.
While filming the scene in which Saul runs into a tree, James Franco became overzealous and actually ran into the tree, causing him to get three stitches.
When James Franco smashes the bong over Danny McBride's head, it was supposed to be a fake, breakaway bong so McBride could take part in the stunt. However, it was filled with some water, and when Franco actually smashed it, McBride was mildly hurt.
As he is handing Dale some guns, Red (Danny McBride) says, "Ted Jones messed with the wrong melon farmers." This is a reference to the common network television practice of dubbing over swear words with less objectionable words, or terms that have a similar sound and length - even if the replacement words don't really make sense in the context of the movie. "Melon Farmers" is used most famously as the dub for "Mother F***ers" in the network television version of the Die Hard film franchise (in which lead character John McClane's famous catchphrase, "Yippie-kai-yay, Mother F***er!," became "Yippie-kai-yay, Melon Farmer!").
Seth Rogen told the April 25 issue of Rolling Stone magazine that the filmmakers originally wanted a budget of $50 million, but was only able to secure $25 million, due to the drug-heavy subject matter.
Saul's grandmother was not part of the original script. James Franco came up with the part, suggesting that it would be funny for his drug dealer character to have a Bubbe.
Rosie Perez convinced director David Gordon Green to cut most of her dialogue out, telling him it would make her character's crooked side more effective and ultimately more mysterious.
Seth Rogen was a guest on The Howard Stern Show (1990) on August 11, 2008, and he told Howard Stern that he wrote the script in 2001. However, since he was still relatively new, it wasn't until his performances in The 40-Year-Old Virgin (2005) and Knocked Up (2007) that the script was approved.
Dale asks "Where should we go?", Saul answers "I dunno, hotel, motel, Holiday Inn?". These words are part of the 1970s hip-hop song "Rapper's Delight" by Sugarhill Gang.
The red Slurpee Saul spills over the windshield of the cop car was darkened in the trailer after it was discovered that audiences were mistaking it for blood.
Seth Rogen had to practice yoga, to be more limber for the more physical scenes in this movie.
During a July 2008 interview with the Orange County Register about this movie, the interviewer told Seth Rogen and James Franco that he prepared for the interview by watching the classic stoner comedy Fast Times at Ridgemont High (1982) the night before. When he asked Rogen and Franco if they prepared likewise before making this film, Franco said he prepared by making out with Spicoli (a reference to his having shot Milk (2008), in which he and Sean Penn play lovers).
Judd Apatow told the newspaper "USA Today" that James Franco read Homer's ancient epic "The Iliad" during breaks on the set.
The first time Dale visits Saul, he apologizes for coming up before being buzzed in, to which Saul replies, "Stuff your sorries in a sack, man!" This is actually from an episode of Seinfeld (1989), where the characters disagree over whether or not the quote is a commonly used expression. Ironically, after the popular episode aired, and was replayed over and over in syndication, "Stuff your sorries in a sack", actually did become a casually and commonly used expression, as seen here in this film.
Co-producer and co-writer Judd Apatow says that the inspiration for this film came from watching Brad Pitt's drugged-out character Floyd in True Romance (1993). Kevin Corrigan appears in both films.
James Franco had stated in an interview with MTV news--and Judd Apatow stated the same at a Comic Con event--that they had considered making a movie sequel that would intersect the story lines of this movie and "Superbad (2007)." This never materialized.
In the original script, Dale's girlfriend Angie was an adult and a strong mature businesswoman in sharp contrast to her slacker boyfriend. The decision to rewrite Angie as a high school senior was done to avoid unfair comparisons with Shaun of the Dead (2004).
Scene just before Dale calls Angie crying (1:12:15), girl in a red shirt and jeans walks by, which is Lauren Miller Seth Rogen's wife in real life.
The place where Saul and Dale are held hostage is where the beginning of the movie takes place underground. In the back of the room, you can see the water suit in which the people used when testing the effects of marijuana.
Olivia Thirlby was cast as Angie Anderson, but was replaced by Amber Heard after rehearsals.
Though James Franco's character (Saul) is a drug dealer and heavy marijuana user, Franco does not actually smoke marijuana.
Saul's grandmother or Bubbe has a different last name than him, Belogus, which he says to Dale at one point during the movie. Seth Rogens mother's maiden name is Belogus.
Saul (James Franco) carries a Taconic High School duffle bag in almost every scene of the movie. Taconic High School is a public school in Pittsfield, Massachusetts. The school's mascots are "The Braves", and the colors are green and yellow.
When Seth Rogen gave James Franco his jacket in the woods Seth's t-shirt can be seen under his dress shirt. It says Tomato Face and number 54.
Trifecta doesn't actually mean anything related to the special T-shaped joint or the smoke inhaled. It means "a bet which is won by correctly selecting in the correct order the first three finishers in a race."