Gallas, 30, lost his cool during the dramatic end to the Barclays Premier League match at St Andrews, which saw the home side snatch a last-gasp equaliser from the penalty spot.
There have even been reports some senior Arsenal players had to calm their skipper down in the dressing room as Gallas continued his emotional response to what had been a difficult afternoon.
However, manager Arsene Wenger has expressed complete confidence in his "outstanding" captain.
Speaking in his matchday programme notes ahead of the clash with Aston Villa, the Arsenal captain said: "Maybe it should not have been a penalty against us at the end, but the referee whistled for it so there is nothing you can do - that is difficult to accept.
"I was very angry at the end of the game, very angry because I am a passionate man and I know how difficult it is to win the title.
"I was angry about a lot of things, nothing in particular but everything which happened that day had built up.
"We dropped two points in the last minute, and if we go on to become champions this season, it will not matter - but if we don't win it, everybody will look at those games against Birmingham.
"We made a mistake and it is difficult to answer how much that will hurt us until the end of the season."