Reba Eats and Pterri Runs - S3-E1
Visible crew/equipment: As Pterri comes around to Reba's left side, the puppeteer's hands can be seen behind her back for a moment.
Monster in the Playhouse - S1-E9
Revealing mistake: As Reba the Mail Person exits the Playhouse, she goes past the window, and you can see her exit the sound stage through a door painted the same as the background.
Salesman: I'm going door-to-door to make you this incredible offer.
Pee-wee: Aaaaaaaaaaaaaahhhhhh! salesmen.