It is not clear whether this is a mistake or a hint that the Baron is alive, but in every scene that the Baron is shown, he looks different than the time before (position of hands, cane and hat).
(At 22:56 - 23:20) When Shizuku first follows Muta the cat into Mr. Nishi's antique shop. Just as Shizuku watches Muta enter the shop, we are shown a golden pig statue sitting on the ground being used as a door stop to hold the shop door open, with its head angled so that it is looking to its right (to the left from our perspective.) But in the next scene we see that the pig's head is not angled to either side at all - and is instead shown looking straight ahead.
(At 08:45) When Shizuku and Yuko are sat on the bench singing "Country Roads", Yuko is holding a piece of paper which is hole-punched down the side. The punched side is on her right (closest to Shizuku), but when the angle goes wider, the paper has flipped and the punched side is on her left.
At 18' : Traffic light changes to blue, not green.