The Owls looked set for three points after Gary Hooper’s second-half double overturned an early Fraizer Campbell goal, but Michael Dawson snatched the Tigers a draw in the fifth minute of stoppage time.
Despite Wednesday extending their unbeaten run to seven games, Carvalhal is a man under pressure given the manner of his team’s performance.
The Hillsborough crowd let their feelings be known at half-time after a miserable opening 45 minutes and then exited en masse when Dawson levelled.
Carvalhal focused his post-match anger on referee Michael Jones, who denied his Owls a penalty for an apparent handball before Wednesday scored their second.
The Portuguese was sent off for his appeals and unleashed his frustration after the game with a 12-minute rant.
“I’m very upset, not about my players, because we did everything we had to do, not about myself because I did everything I had to do,” he said.
“But there was an unbelievable penalty, the defender acted like a goalkeeper, it is very clear. I am very upset because everything comes to me.
“With these kind of decisions, it’s not just about the points. The fans are not happy with the score, we are not happy, the players are frustrated and it is not about the decision.
“We lose points, one point here, two points, one point, three points, two points in this case.
“In the last 10 games we have been living with these kind of situations and you know this is not something I imagine. You know that.
“Let’s see the Channel 5 programme and let’s see them analyse and see if it was a Sheffield Wednesday penalty.
“It’s a clear penalty and we will see on television. One more time, one more time, like the music. We have lost 10 points and with them I would be in a different position
“This is the reality.”
Hull boss Leonid Slutsky is taking his future one game at a time and this draw may prove to be a stay of execution.
The Russian has been on the brink at the Tigers for the last 10 days and his position looked like being even more precarious until Dawson intervened late on.
The result could keep Slutsky in his job, but he is not looking too far in advance.
“I don’t know about my future,” he said. “Each match is very important for me, and it is very difficult for me to think about the future.
On the game he added: “We deserved a draw and deserved it for previous games because we have been unlucky and conceded late goals.
“I try to analyse the game and now I understand our problem because when we score a goal we stop trying to play and keep the lead and this is not our strength. We don’t have a big forward and have the possibility to keep the ball.
“In the first half we played really well, we controlled the game and we scored. When we sit deeper it is very dangerous.”