Les makes his frequent mistake during the first "Supermatch Game" of saying "points" instead of "blanks". However, unlike in other instances, he doesn't correct himself.
The second answer in the second "Supermatch Game" gets momentarily stuck when being revealed.
Around the 23'15m mark, Lynsey de Paul brushes material past her microphone, causing a rustling sound.
In the final tie breaker game, Jeff Stevenson can clearly be heard saying "chisel" aloud while thinking of his answer. Had the contestants overheard, it would have allowed them to cheat: as one of them matched Jeff's answer, there's the possibility that this did actually happen.
When Lonnie Donegan gives his guess for the second "Supermatch Game", Les turns and yells it at the board in the tone of voice he uses to reveal the answers, seemingly forgetting the answers aren't revealed at that point.
Les's body language seems more mannered and stiff than normal in this episode, and he's slower than usual when describing what happens next in the quiz. As he's conscious of hitting marks for the cameras, and isn't completely sure of the rules, this would suggest that it was one of the earliest to be recorded - yet it could have been down to tiredness, as this was the second episode to be recorded that day.