Gallagher told Sky Sports News: "I think there is [enough contact for a penalty]. When you see the incident, the clue is the ball - Bellerin doesn't get the ball, and once you don't get the ball in that situation, he's caught Hazard on the inside of the boot and therefore he's duty bound to give a penalty.
"Does Hazard exaggerate? I don't think he has time. Bellerin's caught the inside of his boot, Hazard's only got one leg on the ground, his other is in the air, and he's trying to keep his balance and the minute he's done that he's going to go over, there's no doubt about it. But the key is Bellerin didn't get the ball.
"It's so subjective, that's the problem. Every decision is subjective to the referee. In that situation, Bellerin has not got the ball. If a player makes a tackle and he gets the man and not the ball, the referee has got every right to give the penalty."
The encounter at the Emirates Stadium ended in a 2-2 draw.