Daryl Murphy had fired Ipswich into a 30th minute lead, before Steve Davies levelled matters early in the second half.
And McCarthy did not mix his words at Ashton Gate saying: "I'm angry, livid and totally devastated.
"One long ball has taken out three of our defenders for the winner and that simply shouldn't happen. It was a dreadful goal to concede.
"We had a great chance to go 2-0 up in the first half and opportunities to win the game near the end. I should be happy because we played well for long periods.
"But that means nothing. We should not have lost and my weekend will have a black cloud hanging over it."