Other mistake: Early in the film, Jim Carrey is watching TV during a sports segment. He is watching Channel 7, the station he works for. This clip they showed was of actual WKBW sports director John Murphy. The clip they showed was taken directly from a real WKBW newscast, with the authentic news set, and graphics. However, when they show a clip of Ch. 7 News later, there are completely different graphics, and a completely different news set, both made for the movie.
Continuity mistake: After the riot in the streets of Buffalo, Bruce meets up with God again in the Omni Presents building. They discuss how everything is going wrong. At the close-up shot of Bruce's face when he says, "What do I do now?" the frame is flipped. You can tell this because his hair is parted on the wrong side and his nose looks different.