I also don't think it's as bad as the picture makes it look, but he does leave his foot in there, and then also puts his other foot in there too. Probably a yellow card offence.
We had a penalty and were down to 10 men. If the ref had got it right, we'd have had a penalty (for the clear foul on Murray) and not been down to 10 men (as Duffy wouldn't have clashed with VanFallover if the penalty had been given).
So Palace are lucky it wasn't worse.