After the announcer says that Miss Van Loon would be eternally grateful, Dobie stands up and turns the TV set to the left and stands by the set facing his father. The announcer then mentions the $500 reward for the return of "Boo Boo", and in the next shot Dobie is back in his seat.
When Maynard is sitting on the box and gets pushed up to the counter, there is a wire rack of goods at the end, which Maynard pushes slightly, but in subsequent shots the wire rack is gone.
After Dobie turns on the TV set, when he twists it before sitting down, if you look at the holes in the back of the set you can make out the opposite corner of the cabinet indicating that it's empty.