In a post-match interview containing more than a few expletives, McCarthy demonstrated his frustration at seeing former Town striker Jon Stead net a last-minute winner.
"I'm angry, livid and totally devastated," said the manager.
"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."
Stead broke on to a header from fellow substitute Steve Davies and took his time before beating Scott Loach with a low left-footed shot from 10 yards.
Ipswich had been the better side and deserved to lead when Danny Murphy shot past Tom Heaton after forcing his way beyond Liam Fontaine on the half hour.
But Davies blasted an unstoppable left-foot equaliser from a narrow angle after he was picked out by Paul Anderson's 47th-minute pass.
And Ipswich were left to rue one of the misses of the season by Lee Martin on 37 minutes when he fired wide of an unguarded net from six yards.
- Sports & Recreation
- Jon Stead