Michael Keaton had previously played Batman. Nicole Kidman went on to play Batman's love interest in Batman Forever (1995) with Val Kilmer, and then appeared with subsequent Batmans George Clooney in The Peacemaker (1997) and Christian Bale in The Portrait of a Lady (1996).
When they are leaving the airport in Detroit, to go back home, there is clearly a palm tree in the background, just outside the terminal. Palm trees don't grow in Michigan.
In the scene where Bob is videotaping the hotel room, he zooms in on Gail's stomach, which is very large and round, expecting a child. In the next scene at the wedding reception, it shows them dancing around, and her standing there clapping, and there is no pregnancy belly.
When Bob is at the amusement park & walking down the ramp to get on the roller coaster (which is really Colossus at Six Flags Magic Mountain in Valencia, CA), it's obvious he is going the wrong way down the exit ramp rather than using the real entrance. In the next shot, he is shown on the other side of the roller coaster track getting into the coaster.