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: 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 Richard knocks out the gardener that's holding a knife, the knife lands right next to the gardener's hand (it's touching him). When Richard and Larry go to drag the gardener and the other guy, the knife is a lot farther away from the gardener's hand.
Factual error: In the lunch scene outside their office, Larry and Richard are at the food stand and notice Bernie walking into a building. The entrance awning reads "East 70th Street". As they walk away the street sign behind them reads "52nd Street". Apparently they must have superhuman vision which allows them to see 18 blocks away.
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: When Larry and Richard arrive at Bernie's house and talk to the lifeguard out the front, there is only sand leading up to the house. Later when Richard leaves the party and runs onto the beach to see Gwen, and at the end when Bernie is being taken away by ambulance, there is now a wooden walkway leading down onto the sand.