Continuity mistake: When Rodney and Del are coming out of the casino in the morning as they're coming down the stairs they don't have their coats on, in the next scene they do.
Revealing mistake: When Rodney is holding Damien, it shows a shot of it in the mirror, the next shot is from behind the mirror and he is holding him the different way round.
Suggested correction: This was during his dream, so probably plausible in those circumstances.
Revealing mistake: When Slater asks if the baby will be named after him and Rodney gives his answer, camera shows Del and you can quite see David Jason doing his best not to burst into laughter because of Rodney's answer.
Suggested correction: After Rodney gives his answer, the camera cuts to Slater, and then back to Del. He isn't close to bursting into laughter. He only laughs when he and Rodney stare at each other after Slater has left the pub, which was certainly the original intention.