Revealing mistake: At the very beginning of most episodes of Series 1, during the pre-credit scene, either Paul or both of the brothers can be seen waiting for their cue. It usually lasts between one and three seconds.
Revealing mistake: In "Stop That World, Series 3, when Barry gets thrown of the See-Saw by the globe, and Barry lands in Paul's arms. The first shot is of a dummy and quickly switches to the second shot of Barry. It is obvious they used a dummy to make it look like Barry was falling into Paul's arm before switching them quickly.
Cycle Crazy - S3-E13
Revealing mistake: In "Cycle Crazy, Series 3, Paul rides through the tunnel on his bike only to ride out again when a big truck comes the same way. It is obvious that the shot of Paul and the lorry are two separate shots, because after Paul comes back out, the trees don't follow the same pattern as the previous shot. This also happens between the shots where Paul rides into the tunnel.
Revealing mistake: When the robot refuses to let Paul and Barry through, they attempt to go under his arms but they are thrown aside. It is obvious dummies are used, because of their floppy features and blank faces.
Parks and Wreck-Reations - S3-E2
Revealing mistake: When Paul and Barry are chasing the lawnmower, just before they go out of shot, Paul stops, triggering the end of his cue.
