In the third minute of the Premier League fixture at the King Power Stadium, Kompany committed a professional foul on Jamie Vardy, only for the referee to caution the Belgian international rather than dismiss him early into his first appearance in two-and-a-half months.
While acknowledging that the centre-back should have been sent off, Gallagher has claimed that the referee would have believed that John Stones was in a position to cover for his teammate.
Gallagher told Sky Sports News: "I think the difficulty here for the referee is that he is behind the incident. What he doesn't see is that Vardy is in control of the ball. When he looks up after the foul, he sees that John Stones has come across.
"The whole situation has changed. He can't snap-photograph it in his mind like we can. If you see if forensically, it's a red card. if you see it as a referee, he is deceived because of the ball going away."