When Henry drops the knife, it is a foot or more from the wet spot that he had been dragged through. When Calvin tries to pick it up seconds later, it is in the center of the wet spot.
When Teddy is holding his shoes out after the boys clean them, he is holding the right shoe in his left hand and the left shoe in his right hand as they would appear if being worn on the wrong feet. In the next shot, they are reversed.
The movie is set in 1944, in the part they show North Beach the Harbor Bridge is shown but it wasn't built till 1956