According to one of the featurettes on the DVD, several of the shots in the movie were added after initial filming ended. These included the scenes of Rudy and Tripper at the bus station and of them playing blackjack for peanuts. During the time off, Chris Makepeace had entered puberty and had the beginnings of a mustache. Bill Murray decided that it had to go so he took Makepeace over to a sink, lathered him up with soap and shaved off his mustache. So Makepeace received his first ever shave from Murray.
John Belushi convinced Bill Murray to accept the part of Tripper, pointing out that it would be Murray's first film and he would be the star.
First starring role of actor-comedian Bill Murray. Murray had sole name above the title billing on movie posters.
First of six collaborations of Bill Murray and Harold Ramis with Ramis functioning in any combination of various roles as actor, writer, director. The movies include Les bleus (1981), Arrête de ramer, t'es sur le sable (1979), Le golf en folie ! (1980), S.O.S. fantômes (1984), S.O.S. fantômes II (1989) and Un jour sans fin (1993).
While filming the social/dance scene that happens after the Camp North Star-Camp Mohawk basketball game, the cast wasn't actually dancing to "Makin' It" by David Naughton (the song was inserted in postproduction after permission for its use was secured). "Miss You" by The Rolling Stones was played again and again while shooting the scene.