Continuity mistake: Right before Richard discovers that Bernie is dead and Larry is talking about drugs becoming a career, "I watch the news. I read." There is a side/back view of Larry talking and neither his gestures or his mouth line up with what he is saying.
Other mistake: In the opening scene in the office, when Andrew McCarthy says, "Let's go to the beach" and runs off, you can see that the other guy's PC, which he has been working on, has no power cable plugged in.
Continuity mistake: At the end of the movie, when the hitman comes to kill Bernie for one last time, Larry, Gwen, and Richard start running from the hitman and Gwen has her hat in her hand. They run over to the stereo and she drops it somewhere over by there. In later shots, however, you can see Gwen's hat lying right next to Bernie in front of the staircase.
Continuity mistake: When Larry and Richard are piling into the crowded elevator Monday morning with everyone, some of the people who get on are different from who we see riding up. In particular we see the door close on a girl in brown with a green purse strap before she can get on, but she is seen riding in the elevator in the next shot.
Continuity mistake: When Larry and Richard listen to the recording of the phone conversation between Bernie and Paulie, there is a slight difference to when they had the conversation live. After Bernie told Paulie where his house is located, Paulie replied with "Uh huh" which is not heard on the recording.
Continuity mistake: In some scenes you can see Bernie breathing and blink his eyes when he is supposed to be dead.
Continuity mistake: At the end of the movie, when the ambulance is shown backing up to Bernie's house, you can see a stretcher on the boardwalk that gets bumped and rolls down. This stretcher has Bernie on it, yet when it is bumped it is completely empty.
Factual error: Throughout, Richard, who is supposed to be young, single and living with his parents, can be seen wearing a wedding band.
Continuity mistake: Just after the hit man kills Bernie he proceeds to disguise himself and pulls a folded, floppy beach hat out of his pocket. Yet when we see him getting on the boat in the next scene the same folded hat is now a perfectly round, structured hat with a brim.