In the "Ripped Pants" episode, there is a shot that shows the changing tent SpongeBob is in while he is thinking about what he can do to win back his friends. Now look at the shadow of it. This angle would be alright, that is if the umbrella in the background had its shadow facing that way too. If you look you can see that the shadow of the umbrella is facing the exact opposite direction of the shadow of the tent.