Revealing mistake: The first morning the new Mrs De Winter is at Manderley, she goes to have breakfast, but when she attempts to pour milk into her coffee, there's no milk in the jug; she's just pretending to pour it.
Continuity mistake: Near the beginning Harriet Vane produces tokens for herself & Lord Peter Wimsey of miniature handcuffs with one cuff "open to symbolise we're giving up on crime". She puts hers on as a bracelet. Immediately after & several times throughout the film it's clear hers is a set of closed handcuffs.Christopher Walters
Other mistake: It's the Professor's 60th birthday and the candles on his cake must be the trick type - they keep going out as the cake is carried into the room, but they quickly come back on again. But when it comes time for the Professor to blow them out, there's no problem - he blows them out easily.kh1616