On the Road - S2-E1
Revealing mistake: As Cassidy, Tulip, and Jesse are trying to outrun a police car, another cop car enters the road in front of theirs with tires squealing. There are tire skid marks On the Road before the cop car enters, indicating previous takes of the same stunt.
Revealing mistake: Janet is holding a coke in her hand that she is supposed to be conjuring up but is already holding it.