Revealing mistake: The crane in the garden is behind the tree, but we see just the top of it - and under it is nothing.
Race to the Spaceship/Sandbox Surprise - S3-E5
Revealing mistake: In the sequence where Pig is making a pizza with strange toppings, an ant caries a large bucket of popcorn up the counter. It is flush on its back with no top when on the floor, and the popcorn is bulging out. The ant turns 90 degrees and walks up the counter, and the popcorn thus turns on its side in the air. Not one piece of popcorn falls out or even shifts, despite the pile now pointing out rather than up.