The Blades defender was dismissed on 27 minutes for lifting his foot off the ground and made contact with McAllister's back. But United may appeal to get Kilgallon's dismissal rescinded.
Gaffer Kevin Blackwell said: "Killa put his foot up and their lad ducked down a bit but it wasn't malicious, and if that was a sending off then we can't play football anymore.
"But the way the game is at the moment I can't go and speak to the referee about it because I will get a heavy fine.
"Brian Howard has got a lump on his eye from an elbow and Kyle Naughton also has a sore head from another challenge - but we get a sending off for much less!"
Unsurprisingly referee Mike Dean declined interviews with the press.