The Premier League has admitted that VAR got penalty decisions wrong in all three matches on Thursday, as frustration mounts over the use of the technology in the English top-flight.
Manchester United were given a controversial helping hand by the video assistant referee in their 3-0 win at Aston Villa, while Tottenham suffered fresh frustration from the review system in their 0-0 draw at Bournemouth.
United midfielder Bruno Fernandes won a spot kick when he spun into Ezri Konsa before tumbling in the area despite little evidence of a foul by the Villa defender.
Jose Mourinho's Spurs were off-key for long periods but could feel hard done by after Josh King's push on Harry Kane in the penalty area went unpunished despite a VAR review.
Southampton's James Ward-Prowse hit the bar after a disputed penalty as the south coast side drew 1-1 with Everton.
The Premier League confirmed to the BBC's Match of the Day programme that United and Southampton should not have been given penalties, but Tottenham should have been awarded one.
Former Everton midfielder Tim Cahill, a Match of the Day pundit, said a former player should work alongside VAR officials.
"I think that would really help them, to understand the movements," the former Australia international said.
"When a player falls to buy a penalty you can feel it. It must need a player there to give advice on what the player is doing.
"They're there to make the big decisions and they can't do it. It's really disappointing."
Mourinho refused to speak about Michael Oliver's appointment as referee for Sunday's match against Arsenal at his pre-match press conference.
Oliver has been the VAR official for Spurs' past two away games. There were controversial decisions in both -- a Harry Kane goal was chalked off for a Lucas Moura handball at Sheffield United and no penalty was award at Bournemouth.
Mourinho believes referees and VAR officials should be made accessible after games to explain their decisions.
"I think you should have access to them, I think you should have access to them to ask directly why," he said.
"It is very important. They are very important in the game, I think so.
"It would stop nothing, make things much more open, much more clear. It would give the ref the chance to say, 'Yes, I made a mistake -- I feel sorry for that', or 'Yes I had incredible performance'."