When Dr Livesey's coach knocks down Blind Pew he lies length ways as the horses go over then but is then seen width ways as the coach passes over him.
When Silver undertakes his escape at the end, he uses a belaying pin to knock out Gunn. In the next frame Silver no longer has the pin in his hand, just a bottle of rum, which he uses to sprinkle rum over Gunn (to make it appear Gunn has drunk himself into a stupor).
When Jim gets to the island a monkey, in the crown of a coconut palm, throws a coconut down at him. But as monkeys would have no way to get to remote islands there would be no monkeys on "Treasure Island."
The Captain sings the first two lines of a sea chantey and tells everyone in the tavern to sing along. They sing not only the first two lines again but the rest of the song, although they have not been told it.
When Silver and Jim enter the tavern that Silver claims to own, there is a seated man playing the mandolin. But as the man plucks the strings, his hand is clearly and obviously no where near the strings (they are at least three or four inches from the instrument).