Referees' body PGMOL says "human error" was to blame for incorrect VAR decisions in games on Saturday.
PGMOL chief Howard Webb has contacted Arsenal and Brighton to "acknowledge and explain the significant errors" that occurred in their games.
VAR operator Lee Mason did not draw the guidelines to check for offside on Brentford's equaliser against Arsenal.
What happened?
During the 1-1 draw at Emirates Stadium, Ivan Toney's 74th-minute goal was the subject of a VAR check by Mason following Ethan Pinnock's challenge on Gabriel.
That incident was cleared but there was a suggestion Christian Norgaard was offside in the goal's build-up.