Audio problem: When Joey is standing under the waterfall to cool off, he is heard sighing, but his mouth doesn’t move. (00:15:11)
Revealing mistake: Just as the episode ends, the main characters are walking through the portal. When the shot is pulling back, they are walking, but they don't appear to be moving forwards. They are just repeating the same walking animation. This becomes apparent when the door frame is visible in the shot, and it's clear they aren't moving forwards. (00:20:35)