I watched Spiderman the other night and noticed when Peter was just learning to use his web, he shot at a lamp, hit it and pulled it back breaking it. Aunt Maye knocked on door to see what was wrong and Peter said everything was ok. When he closed the door, the lamp was back up on the shelf unharmed. Bizarre  ???

Also when Disney rereleased Bambi a few years back, at the very end of the movie when Thumpers wife(?) was petting her baby rabbit, it mysteriously disappeared leaving her gently stroking the air, hmmmm........................

Any others??

I don't know if this is a 'mistake' in that sense, but I do think it's (terribly) historically inaccurate...

Titanic

When Jack and his friend have made it onto the boat and gone up to the bow, and are standing right up at the front on the railing and being exhilarated...

Jack screams out "Wooooooooo, Woooooo-Hooooooo"

Apart from my personal dislike of the use of that sound (only due to it's overuse - OK - I'll stop being grumpy now  ;)), this sound is a reasonably recent phenomenon, going back no earlier than the 70's.

I doubt an Irishmen in 1912, no matter how brash and/or outgoing he was, would have uttered that sound.