Plot hole: When Gloria picks up Scotty on the road towards the beginning of the movie, they are being followed by the black car. But if Scotty had been being followed, the car would have easily caught up to him when his car broke down. (00:09:20)
Continuity mistake: When Scarface is holding Gloria as he asks "Where is it?", watch her arms - from the side, we can see her left arm is arched outward; however, from the view behind Scarface and facing Gloria, her hands are pressed together in front of herself, in a defensive position. (00:38:55)
Plot hole: When the albino kidnaps Gloria in the middle of the day, he is looking for the film obviously. So he would have checked her purse for it because that's where it most likely would be if she'd had it with her. But if he did check her purse, he would have seen all that "equipment" from Stella in there. But Gloria still has it when she comes to consciousness. What kidnapper would leave weapons in her reach? (00:48:35 - 00:50:05)
Other mistake: After Carlson and Gloria have escaped their captors, they have to get to the Opera House ASAP to try to thwart the assassination of the pope and have to use 3 vehicles. I have frequently visited SF from the UK, and am familiar with the layout of the city. The route they take seems bizarre. They keep coming back on themselves, and at one point make a left onto California St behind a cable car. All they then needed to do was continue to the junction with Van Ness, take a left down to the Opera House near the intersection with Market St - yet still go off-route. I appreciate sat-nav hadn't yet been developed, so perhaps the film-makers were trying to evoke memories of Steve McQueen's car chase in Bullet.