Plot hole: When the watch is sucked to the island by the magnet, where was the sailor that the watch was attached to?
Revealing mistake: When Max and 99 are rowing away on the Chief's inflated diving suit, you can see that the Chief is not in the suit and it is just an inflatable raft.
Revealing mistake: Siegfried uses the magnet to push the ship away from the island. However, you can see the scene is reversed; the steam from the ship is going back into the funnel.
Revealing mistake: When Max accidentally shoots the life raft with the flare gun, he visibly doesn't make a hole in the raft. It's likely it's ink or ash or another black material to look like the raft had a hole burned through it.
