Evan Goldberg created a game for himself during filming. The goal of the game was to get as many cast members as possible to say, "No I can't do that" or get them to refuse to do something. According to him, the only people he wasn't able to break were James Franco and Seth Rogen.
Initially Michael Cera wasn't really slapping Rihanna's butt, but rather making the motion and stopping right before touching her. As a result, the scene wasn't working on camera because it looked too fake. Eventually Cera asked Rihanna if he could really slap her butt, she said yes but on the condition that she be allowed to really smack him across the face each time. Cera agreed.
The day Seth Rogen filmed the first scene of the movie where he goes to pick up Jay Baruchel at the airport, is also the same day he filmed a special feature for the movie Paul (2011). Rogen never bothered to change his wardrobe and is wearing the same clothes in both movies
In an interview with the Rod Ryan Show on Houston radio station 94.5 The Buzz, Craig Robinson revealed that Jonah Hill improvised asking for a bite of the Milky Way. The other actors improvised the following conversation regarding who gets to eat the Milky Way.
Seth Rogen said that he was shocked by how much the actors would insult each other. According to him, Jonah Hill and James Franco in particular seemed to go at each other the hardest. At one point he felt like he had to intervene and remind them that they are actually friends and like each other.
According to Seth Rogen, Danny McBride was the person who made everyone laugh and break character the most. At one point, it took 18 takes and over an hour for the cast to get a joke on film because Mcbride's delivery kept making everyone laugh.
The bright, colorful windbreaker that Michael Cera wears in the movie was his idea. According to Seth Rogen, this was the only condition Cera had before agreeing to be in the movie. This shocked Rogen, who thought that he would complain or be unsure about the inappropriate behavior that was in the script.
Jay Baruchel admitted that despite all of the hilarity and the over the top nature, making the movie was actually therapeutic because he felt that some of the arguments and confrontations in the movie were on some level things that the actors have actually wanted to say to each other at some point in real life.
Seth Rogen and Evan Goldberg made the decision early on in the process to not include any significant others or family that the actors have. They felt that if they had to deal with this aspect, the movie would get too dark. For example, Danny McBride was a newly wed and had a new baby but there was no mention of this, and Rogen's soon-to-be wife Lauren Miller was not shown during the scene where Rogen and Jay Baruchel enjoy their afternoon of video games and smoking pot. James Franco suggested having his brother Dave Franco (who is friends with the group and is also an actor) in the early party scene, but Rogen rejected the idea, saying that he would eventually have to get killed off and it would be too depressing.
Seth Rogen stated in an interview that at one point during production every main cast member took him aside and told him that they couldn't do what he was asking him to because it was going too far and getting too extreme. James Franco was the only cast member that never turned anything down.
Seth Rogen gave an interview where he described how the script by himself and Evan Goldberg combined real characteristics of the actors who then produced bizarre alt-version of themselves with elements that had absolutely nothing in common with the cast. Craig Robinson echoed this point in a separate interview when he said that that Michael Cera's portrayal in the film - a drug-using, ass-grabbing, utterly obnoxious loudmouth - was "the epitome of NOT Michael Cera".
Originally Seth Rogen and Evan Goldberg asked Sony for a $40-$45 million budget, but Sony was nervous about the plot of the movie and said no. Rogen and Goldberg then asked Sony what amount they would be comfortable giving while still letting Rogen and Goldberg maintain creative control, and Sony said $32 million. Rogen and Goldberg accepted.
Evan Goldberg and Seth Rogen revealed that the early rumors that they had approached Daniel Radcliffe for a part in the movie and he turned it down were true. They admitted that it was in the very early stages of writing the script so not all of the parts were fully developed. Rogen and Goldberg have both stated that they understood why Radcliffe turned it down.
The film was going to be shot in Los Angeles in order to make it easier for the celebrities who would be doing cameos. However, the location was changed to New Orleans in order to save money. The only celebrity cameo that was lost due to the location change was Cameron Diaz.
The film appeared to have finished a very successful North American box office run falling just short of the $100 million benchmark for blockbuster status, with over $96 million in receipts when it fell into very limited release by the end of August 2013. While the $100 million blockbuster goal is no longer considered as unique or important as it once was (due to the combination of higher ticket prices and film budgets, as well as the majority of most major films taking in most of their box office revenue from international markets), Sony Pictures put the film in over 2,000 additional theaters for week of September 6-12, 2013, specifically to aim at getting over the nine-figure benchmark. And on September 14th, its 95th day in theaters, it officially reached blockbuster status.
During the first night where they are sleeping together in the living room and they all keep scaring each other, there is a picture on the wall supposedly painted by James Franco with the title "geeks" on it. It also contains paintings of characters from the show "freaks and geeks" which was where Jason Segel, Seth Rogan, and James Franco first worked together with Judd Apatow.
The trivia items below may give away important plot points.
Originally there was going to be a joke where one of the characters said that they had smoked crack with Whitney Houston. When she died, the joke was cut out of respect and a different joke was used. In addition, while making the film, Seth Rogen and Evan Goldberg were in the process of convincing Prince to let them use the Purple Rain (1984) song for when Rogen and Jay Baruchel make their way to Heaven. After Houston passed away, Rogen and Goldberg dropped negotiations with Prince, and instead decided to use Houston's version of 'I Will Always Love You' in those scenes as a tribute to her.
In a June 2014 interview, Channing Tatum talked about filming his cameo role as a submissive sex slave to Danny McBride's character. Tatum said that during the sequence where McBride and his cannibal gang eat James Franco alive, he was shown holding up Franco's severed foot and drinking all of the blood that poured out of it. However, when Seth Rogen screened the film for test audiences, their response cards were unanimously disgusted by this image. Rogen said it was the only one of the many gruesome and depraved elements of the film they had a problem with and specifically noted they didn't want to see Tatum doing something like that. As a result, Rogen and Evan Goldberg cut the image. That is why Tatum appears to disappear abruptly from his scene, since there was no other footage of him available from the point where Franco was murdered.