Diego Costa scored the Blues' second goal from what appeared to be an offside position and in the process condemned the Canaries to their eighth consecutive Premier League match without a win.
The Spaniard was standing offside when Bertrand Traore slipped the ball forward on the stroke of half-time but the match officials did not disallow the goal much to Neil's dismay.
"He is offside. I've seen it back on the video," Neil said after the match.
"You would expect the officials to get it right. It's disappointing they don't get it right. They'll be disappointed they didn't get it right. But the linesman's called it how he saw it.
"It's not as if he's two or three yards offside. He's probably a yard, half a yard. You'd like to think he would've got that one correct, but when you're down at that bottom end those wee bits of fortune that you look for just don't come your way.
"I made him aware at half-time that he got it wrong and he was offside. The guy's made an honest call and got it wrong. It happens. I'm not going to stand here and lambast him for that.
"We're disappointed, really frustrated, but it is what it is."