Co-screenwriter Chris Miller based the National Lampoon short stories that gave rise to the film on his experiences in a fraternity at Dartmouth, from which he graduated in 1962:
"I was at Dartmouth in the early sixties and I belonged to the outlaw fraternity on campus at that time (Alpha Delta Phi). I always said that one day I was going to write the story of that experience. So, around 1974 or so, I started writing it as a novel and then the novel got cut up into chunks, which became short stories that ran in the Lampoon. The stories were documentary. They were cinema verite. When the script was written, the actual incidents that the two stories were about were the fraternity initiation that I underwent ( The Night of the Seven Fires) and the experience I called Pinto's First Lay.
"I was Pinto in my fraternity. That was my name. In the movie, I think that Pinto is me as a pledge and Boon is me as a senior. All the other guys are guys that are so archetypal that everybody knows them. Everybody had friends like those other guys.
"I think the parts of the movie that were most true to my life were the road trip and what goes on during the road trip. In fact, the guy who was the original guy who tried to get a date with the dead girl was at the premiere. When the incident came on, he stood up and raised his hands in the air just like Rocky."
According to the notes at the end of the film, Babs becomes a tour guide at Universal Studios. The closing credits for this film (and Landis' The Blues Brothers (1980)) include an advertisement for the tour at Universal Studios. The ad says "Ask for Babs." As of 1989, Universal Studios no longer honors the "ask for Babs" promotion, which was either a discount or a free entry.
After the closing credits for Blues Brothers 2000 (1998) there is an ad for Universal Studios Florida. Under the logo the words "Ride the Movies" fade out to "(Ask for Babs)."
Karen Allen (Katy) had just moved to New York City from the Washington, D.C., area and was studying at the Lee Strasberg Institute. "One day I walked by a bulletin board and there was a flyer that said, 'College-Aged Actors and Actresses Wanted for Feature Film.'"
Mark Metcalf (Neidermeyer): "I was doing a play in New York called Streamers. Michael [Chinich], a casting director from Universal came and saw it and liked my performance. He called me in to meet with John Landis. I originally went in for the part of Otter. I was dressed kind of Otterish and Landis immediately started talking to me about Neidermeyer. That was his instinct. He asked me if I could ride [a horse]. I told him I was born on a ranch in Montana and had been riding since I was two. He laughed and said "sure." I lied to him 6 different times and I don't know if he liked the fact that I lied or if he eventually gave up, but he wanted me to come back and meet the producers. A couple of weeks later, I came back and read for them. I did the scene with Michael. It was the scene that had Flounder [wearing a Delta pledge pin on his uniform]. I had my script rolled up because I knew my lines really well and Landis encouraged me to really take it out on Michael, so I was hitting him with my script and using it as though it was a riding crop and abusing him, doing things to him that I would have been arrested for in public life."
At the end of Animal House a subtitle says that Doug Neidermeyer went to Vietnam where he was "killed by his own troops." John Landis' segment of Twilight Zone - The Movie (1983), about racial bigotry, has a scene in a swamp in Vietnam. One of the American soldiers says, "I told you we shouldn't have fragged Neidermeyer."