Paul and Barry head back to their old school but find out it wasn't exactly how they remembered. Particularly if the scheming Gavin Quarmby has anything to do with it.
At the 4:13-4:20 mark, there are two things wrong with that scene. When the door closes when Barry has the plank of wood, it doesn’t look as though the glass has been smashed and then as Paul turns around, Barry doesn’t have the plank of wood on his shoulder. Two goofs in 5 seconds.
To be fair, they probably couldn't afford to smash the glass on camera so had to masquerade the effect using a sound effect instead, but nice spotting with the second continuity mistake.
DoctorVision It’s possible, but when I watched this show as a kid, I never noticed it until I rewatched it again here. That was a terrible continuation mistake when the plank of wood wasn’t on Barry’s shoulder.