The French forward went to ground in the penalty area with Birmingham's Carsley apparently nowhere near making contact with his sliding challenge.
The referee nevertheless awarded a penalty, which substitute Steven Gerrard stroked home to restore parity after goals from Christian Benitez and Cameron Jerome.
Carsley was in no doubt that Ngog was guilty of diving.
He told ESPN: "I was absolutely nowhere near him. It's a joke.
"I knew I didn't touch him and I said to the referee to book me or send me off, it would have made me feel better.
"I'm sure he (Ngog) has got a family, well if I went home having done that I'd be embarrassed.
"You're supposed to be teaching your kids an example and that is just an embarrassing case of cheating.
"But the lad's taken a chance and got his team a point so I'm sure they'll be patting him on the back."
Asked about the incident, Blues boss Alex McLeish added: "This is a shame for the game.
"He conned the referee and got his team a penalty. Peter Walton is a good referee but he got that one wrong. If it hadn't been for the penalty, I thought we'd have gone on to win it."
Under-pressure manager Rafael Benitez conceded it may have been a questionable decision but preferred to talk about his team's dominance in possession.
"We had so many chances and plenty of possessions, at the end we can talk about the penalty - whether it was or was not - but we deserved to win because we had so many opportunities," said the Spaniard.
"I was talking to him (Ngog) and he said maybe it wasn't a penalty but it was 74 per cent possession again in the first half and it is unbelievable.
"I was really surprised, we had clear chances and we were attacking all the time."
Gerrard was forced into action by Albert Riera's first-half injury and Benitez admitted there were more fitness concerns for his already injury-ravaged squad.
"We have some problems, Riera, Yossi (Benayoun), Daniel Agger felt something in his back but I feel Gerrard will be okay."