Visible crew/equipment: Christmas Special 1974: When Harold is playing with the toy bus you can see the camera reflected in its windows.

Revealing: Series 7 episode 48, "Divided We Stand," when Harold and Albert are watching football on TV if you look through the vents in the back of the TV set you can see straight through it. It has no screen.

Revealing: When Harold and Albert are watching football on TV you only see the TV set from the back. If you look through the air vents you can see straight through it it - obviously a prop with no screen in it.

Visible crew/equipment: When Harold finds his toy bus from his childhood as he puts it on the floor you can see the camera reflected in the windows.