During the filming of the opening scene, where Rod attempts jumping over the bus, the stuntman playing Rod actually broke his leg.
Bill Hader's long hair in the movie was not a wig. Instead, he had hair extensions put in, which he wore through the entire summer the movie was shot.
All of Andy Samberg's (Rod's) stunt doubles had prosthetic noses, to make them seem as big as Andy's. Jorma Taccone (Kevin) and Akiva Schaffer played a joke on Samberg, by requesting the prosthetics be larger than his own nose, so he would feel insecure.
The scene where Rod (Samberg) asks Cathy (Britt Irvin) out and starts laughing hysterically was improvised by Andy Samberg.
The scene involving Rod (Andy Samberg) ringing the bell over the pool, followed by the other guys singing along to the bell was completely improvised.
Patricia Schaffer: Director Akiva Schaffer's mother, as an extra in two scenes. She's pelted with flyers by Richardson as she walks to her van, and later, she is shown sitting next to him during the screening of Rod's video.