The Joker Goes to School (1) - S1-E15
Revealing mistake: Batman drives out of the batcave alone. The first bit of stock footage of the car leaving the cave does indeed show him alone in the batmobile. But the very next stock shot of the car speeding down the dirt road shows us Robin sitting in the passenger seat. (00:05:25)
Revealing mistake: Reid's rear view mirror, missing in all the medium shots (processed in-studio with an obvious rear-screen projection), mysteriously reappears in full shot when his Chrysler pulls into the car shop. (00:14:00)