Revealing mistake: In the scene where Lawrence Talbot and Sir John Talbot are talking, Sir John Talbot is blowing out candles, but they are filament lamps, because the third candle lamp actually goes out before he blows on it.
The Wolfman (2010)
1 revealing mistake - chronological order
Starring: Anthony Hopkins, Emily Blunt, Benicio Del Toro, Hugo Weaving
Other mistake: Gwen regrets getting Lawrence involved, saying that if she had never sent him that letter, he would still be in New York. She sent Lawrence a letter when Ben went missing in the theatrical version but, in the extended cut she went to tell him in person instead. Yet the "letter" line is retained in both versions even though it doesn't make sense in the latter.
Sir John Talbot: I don't think they'll kill you, Lawrence. But they will blame you. The beast will have its day. The beast will out.
Trivia: Makeup artist Rick Baker has a cameo appearance in this film. He's the man who whistles to his comrades who are approaching the gypsy camp then a few seconds later, gets killed by the werewolf.