Liverpool have asked Professional Game Match Officials Limited for an explanation on two decisions during Saturday's 1-1 draw with Aston Villa.
The Reds have queried why Villa defender Tyrone Mings was not sent off for a challenge on Cody Gakpo, and why the Dutch forward had a goal disallowed for offside.
Substitute Roberto Firmino scored an 89th-minute equaliser for the Reds.
Defeat would have ended Liverpool's hopes of reaching the Champions League.
Liverpool manager Jurgen Klopp watched the game from the stands as he began his touchline ban for comments made about referee Paul Tierney after his side's 4-3 win over Tottenham in April.