OIe Gunnar Solskjaer said "someone must have been asleep in the VAR office" and recommended they brew some coffee after Manchester United's draw with West Brom.
United were held 1-1 at The Hawthorns on Saturday, with West Brom taking the lead inside two minutes despite Mbaye Diagne appearing to put his hand on Victor Lindelof's face in the process of scoring.
Bruno Fernandes equalised before half-time with a fantastic volley, but Solskjaer's men were unable to avoid dropping points for the fourth time in their past five games.
Referee Craig Pawson awarded United a penalty in the 62nd minute for Semi Ajayi's foul on Harry Maguire; although the England international appeared to be in an illegal position, the decision was overturned despite there being no check for offside.
While he acknowledged the correct outcome was reached, Solskjaer was baffled by the VAR process in overturning the spot-kick.
"I think we all want consistency and a fair game but then again there is human error that we all expect, that's what happens. But the penalty we could have had it today is a clear foul," said Solskjaer.
"If you only look at the clash between their centre-back and Harry it is a foul, but I see Harry in an offside position.
"Someone must have been asleep in the VAR office. Someone needs to brew some coffee because it could have been easily avoided by saying, 'No, he's offside. Done, let's move on.'"
When asked about the decision to allow Diagne's goal, Solskjaer pointed to Maguire having a goal chalked off for a foul on Erik Pieters against Burnley in January.
"It is more of a foul than what Harry gave away against Burnley, put it that way," said the United boss.
"When that goal is taken away from us, if there is any consistency at all, this is a foul as well. Then again being a striker as I was, it would be harsh to lose a goal like this, so both should have stood for me.
"I've not really looked at it, I just saw it live. But consistency is what we need. It is definitely more of a foul than what Harry did against the Burnley kid."
The result left United seven points adrift of Premier League leaders Manchester City, who have a game in hand.
City have won their past 16 games in all competitions and are unbeaten in their last 15 top-flight matches, but Solskjaer does not believe the chasing pack are now in a battle for second place.
"No, I don't think so. No one will give it away this early. This season is so unpredictable, anything can happen. Of course we are not going to settle for second," he said.
He added: "It is disappointing of course. We have come away with two points less than we wanted to.
"The start was difficult. They put us under pressure as you expect when they get the kick-off, and we couldn't clear our lines. Then again, we got 90 minutes plus to score two goals.
"I would rather concede in the second minute than the 92nd. [We] just couldn't get enough big chances."