Continuity mistake: Moving out to Sera, Ben is packing his things in a motel. You can see a half full glass standing on a bed table on his left. In the next shot Ben is pouring alcohol to an EMPTY glass filling it in 1/3 approx. In the next scene glass is half full again and in the next one - FULL. Eventually he is drinking from a glass full of alcohol.
Continuity mistake: In the scene directly following Sera's asking Ben to move in with her, while he is packing his bottles and clothes into the too-small suitcase, he empties his tequila (I think) bottle into his glass (the one on the book) filling the glass, at most, half-way, however, after he says "I'm nuts about you," and picks up the glass, it is completely full.
Other mistake: When Ben and Sera are in the casino playing blackjack, and Ben gets angry and loses control, he supposedly knocks the waitress to the ground. It's a terribly fake looking stunt because Nicholas Cage never even comes close to making contact with the girl playing the waitress. She just falls backward and throws her tray to the ground.
Continuity mistake: When Ben first meets Sera and takes her back to his motel room, they get drunk and pass out on the bed. When Sera wakes up next to Ben several hours later and realizes it's morning, she's wearing strappy sandals with a very high heel. In the following scene when the cab driver drops her off at her apartment, she's wearing flatter sandals with a much lower heel.