Factual error: In the scene where Cates and the other two detectives go to the hotel to arrest Ganz and Billy for credit card fraud, it's highly unlikely that detectives would go alone to question or apprehend suspects without patrol units being with them in case of danger. Furthermore, that isn't even a job that detectives would get involved in, unless they are robbery fraud detectives.
Continuity mistake: In the middle of the film, Nick Nolte and Eddie Murphy are following Murphy's car that was in storage for several years and became very dirty. However, earlier in the film long before Murphy's car is picked up in the garage, there is a scene of Nick Nolte driving through the streets of San Francisco with Murphy's dirty car in the scene. It is the exact same scene, used twice.
Factual error: When Gantz fires Nolte's gun at Nolte, he fires 8 bullets out of a six shooter. (00:18:45)
Continuity mistake: At the end of the movie, as Jack (Nick Nolte) and Reggie (Eddie Murphy) are chasing down Ganz through Chinatown, there's a shot of Ganz's silhouette holding up his gun and slowly cocking back the hammer. As Reggie runs through the alley, Ganz knocks him down, jumps on top of him and you see and hear him cock the hammer on the gun back a second time - even though Ganz has not fired a shot during this sequence.
Revealing mistake: During the Eddie and Nick fight scene, you can clearly see the stuntman for Eddie. He looks nothing like him.