Continuity mistake: In the scene where Theo tries to prank Cliff, and Theo grabs the fake gum, he stuffs the "Bag 'o' Gags" under his shirt. You can see throughout the scene that Theo is holding up the bag with his hand. Later on in this scene, the bag drops. In the next shot, there is something green showing from underneath Theo's shirt (The Bag 'o' Gags). Then in the next shot it is hidden again, being held up by Theo's hand.