Originally in the singing penis scene, Michael C. Maronna's own naked penis was used with a CGI mouth added in. After being screened for the MPAA, however, the filmmakers were told to put a sock on it (literally).
During the "Three is the Magic Number" sequence, there is a shot of the boys performing on stage in tuxedos. Jason Schwartzman can be seen on the drums behind them. This scene was not actually shot for the movie, but, rather, footage from a photo shoot.