Red Rackham's Treasure - S1-E5
Other mistake: Professor Calculus brings the parts for two shark submarines (he stated in the scene prior he would bring two) to the docks in two separate crates. The crates he uses to hold the submarine parts in would not big enough to hold the entirety of the submarine. The crates shown are only a couple of feet wide and even smaller in height, but the shark submarines shown in the episode are much larger than the overall size of the crate. (00:06:50)