While passing the frat-house bus, in the close-up, as the two girls are about to flash, the reflections of the camera and two crew members moving on the crew's vehicle are visible on the glass window.
In the scene where the three men are in jail towards the end of the movie, the jailer that comes to let them out (but is stopped by Ben Stiller) actually plays a cop in the Comedy Central show "Reno 9-1-1". In fact, he may even be wearing the exact uniform he wears in the series. Also, the sheriff deputy who comes off the motorhome yelling "Look, he has rubber boobie!" is also a cop on Reno 9-1-1.