When Roger enters the interrogation room where Stan is being held, there are no coffee cups. Yet once the items in the room are wrecked by Stan to catch Roger, there are now 2 coffee cups on the floor; one is still whole, and one is smashed.
Stan was hand-cuffed to the back of the chair. Yet when Roger re-enters the room Stan is no longer hand-cuffed to the chair, and the back of the chair isn't broken.
Francine is against left-handed people, yet Stan has been shown to be left-handed.