Ross County boss Derek Adams questioned the amount of time added on by referee Craig Thomson after Celtic scored an injury-time equaliser in Dingwall.
The Staggies looked on course to pick up all three points after Richard Brittain had scored a free-kick.
But Commons turned the ball in to the net in the 93rd minute to earn a share of the spoils.
Adams was unhappy with that figure, claiming the full-time whistle should already have gone.
He said: "Obviously I'm disappointed - it was deep into injury time.
"Three minutes - there were no injuries and three substitutes so it should have been a minute and a half."
He added: "People are disappointed not to have won the match.
"We are only three games into it - we have a tough game against Dundee next week but we will still keep going.
"The players are capable of creating chances and that is what we did today."