Ralf Rangnick was seen looking at his shoes in apparent disbelief after Arsenal opened the scoring against Manchester United in bizarre circumstances.
Emile Smith Rowe fired past David de Gea from just outside the area following a corner kick.
De Gea was on the ground with his back to the play as the ball flew past him and into the back of the net.
There was no offside and no foul committed, but referee Martin Atkinson suddenly blew his whistle and went to check up on De Gea.
It was unclear whether the effort was going to stand, but after a VAR check, Arsenal were correctly awarded the goal.
It was at this point, as Man United players began crowding around the referee in protest, that Amazon cameras picked up Rangnick in the stands.
The interim United boss, who is yet to officially take the reins from temporary manager Michael Carrick, appeared to be looking down at his shoes as the Red Devils set about pulling one back.
Cristiano Ronaldo returned to the starting line-up as Carrick made three changes for his final match as caretaker Manchester United boss.
The 36-year-old came into the side along with Diogo Dalot and captain Harry Maguire against Arsenal, with newly-appointed interim manager Ralf Rangnick watching Thursday’s match from the stands.
Arsenal, meanwhile, made two alterations as Gabriel Martinelli and Mohamed Elneny came in for Bukayo Saka and Albert Sambi Lokonga.
De Gea warned his Man United teammates of the problems Arsenal could cause them following his side's 1-1 draw with Chelsea.
"We knew we had to not concede for at least the first 20-25 minutes," De Gea said after Jorginho's penalty denied Man United victory at Stamford Bridge.
"We defended quite well; aggressive. The players gave everything and it was good to see the players running all over the place, trying to play and trying to fight for the club.
"I think from [the Chelsea game] we should take a lot of confidence.
"We know Arsenal are in a good moment, they play well, they are improving, so it's going to be a big game."