When Stephanie listens to the speaker phone, the way her arms are crossed changes between shots.
When Michelle walks up to Rigby to announce herself, not only does she mention her name but gives her address out loud inside a Public Mall which isn't a good idea to do for safety reasons.
When Michelle and Stephanie are helping Joey up, A piece of a large camera is seen.
As a kid, Joey was sent a ventriloquist's dummy that had a painted-on mouth and was useless. For no apparent reason, he has kept it for twenty-plus years in an easily accessible place.
At the end of the episode, Rigby gives Michelle and Denise huge stuffed Rigby dolls. The whole episode takes place in just a few hours, so how could he have gotten a shipment of a brand new product, especially since he knew his scam with the mini-action figure was a success.