The penalty wiped out a 47-yard pass that would've put Dallas in field goal range. Instead, the Cowboys faced a 3rd-and-20 from their own 24-yard line inside the final 30 seconds.
"It made me sick when I watched the TV copy," McCarthy told reporters. "I thought Michael ran an excellent route."
USA Today's Jori Epstein shared comments from referee Tony Corrente about the ruling:
Fox Sports officiating expert Dean Blandino echoed the reasoning: "On the live shot you can see Gallup extend arm to create space. Does Ramsey embellish? Sure. Is it still a foul? Yes. Can't extend arm to create separation."
The NFL scrapped replay reviews for pass interference in the offseason. That probably wouldn't have made a difference anyway given how infrequently officials overturned the call on the field despite evidence to the contrary.
As much as McCarthy might be frustrated with how the final minute played out, the pass interference didn't decide the outcome.
The Cowboys only have themselves to blame after scoring just three points in the second half. McCarthy also turned down what would've been a chip shot to tie the game early in the fourth quarter when he decided to go for it on 4th-and-3 on the Rams' 11-yard line.
Dallas will now have to turn its focus to Sunday and slowing down an Atlanta Falcons offense that gained 506 yards in a 38-25 defeat to the Seattle Seahawks.