When Oscar is explaining to Alan how to tell fake jewels from real ones (and then discovering the ones he has are actually fake) the close ups of Severn Darden are printed backwards. One can tell because his hair is suddenly combed the opposite way it's normally combed.
When Hayes and Curry are trying to decide which window belongs to Christine, he says "bedroom suite", but mispronounces the word, saying it as "suit" instead of as "sweet".