Revealing mistake: When the ambulance is hanging over the cliff, in the wide shot you can see the cable holding the ambulance safe. (00:50:40)
Audio problem: When Martin arrives at Guy's flat, the first time Guy slaps him, the sound is a fraction of a second late.
Continuity mistake: Although this episode takes place during a single day, Boyce and Mac's hairstyles change from scene to scene.
Continuity mistake: In "Caroline's First Day." When Martin is on the computer looking up what his old schoolmates had achieved, in one shot Boyce has his arm around him, in the next shot his arm is by his side.
Continuity mistake: When Rachel, Kim and Karen are sat outside eating lunch Karen mentions her friend having made her sandwiches. The satsuma segment in Kim's hand switches from one hand to the other without moving her hands.
Continuity mistake: When Guy is handing Caroline his key, there is a moment when Caroline's green hair clip disappears from her hair during a close-up, but it then reappears seconds later.
Continuity mistake: We see Martin call his mother three times. On two of those occasions we see him dial her number. But the number that he dials is completely different on both occasions.
Revealing mistake: In the 'dead box' scene, just after Martin says 'you mean they're not new?', Sue White noticeably shifts slightly to the left before answering, and does so in a VERY unnatural manner. NOTE: although the show often uses time lapse editing, this is not one of those occasions. It is clear from watching the scene that it was two separate takes spliced together to appear as one shot, with the actors trying their best to replicate their positions from the previous take for continuity's sake.