Morocco star Nordin Amrabat appeared to label VAR "bull****" after his nation's 2-2 draw with Spain, which saw the 2010 World Cup winners progress to the last-16.
Former Liverpool striker Iago Aspas scored a last-gasp goal to put Spain through on Monday night, but the winner was initially adjudged as being offside.
VAR was called into action, with the game being stopped for a few minutes while referee Ravshan Irmatov referred to the video system.
After reviewing the tape, the match official decided Aspas was onside and awarded the goal, sparking anger among the Morocco team who suffered defeat so late on.
VAR also played a big part in Portugal's 1-1 draw with Iran, with the referee referring to the system at least five times.
The system influenced his decision to award Portugal a penalty before it was later used to determine whether Cristiano Ronaldo should be shown a red card.
Speaking about the system in the BBC studio, Alan Shearer said: "Wasn't it meant to clear everything up?"
He added that it has instead increased players arguing with the referee about decisions, saying: "We saw more of it tonight, players running up to coaches, and making the sign".
Didier Drogba attempted to provide a counter-argument, saying: "We have to remember that it's the first time we are using this in a major tournament, so it will take time to adjust."
With Gary Lineker added: "It's still down to human interpretation, and while you have that you will always get mistakes."
To which Shearer hit back: "But it shouldn't be on trial at a major tournament."
Fans watching the action from both games also had plenty to say about VAR on Monday night, and unsurprisingly not much of it was good.