Forest were 2-0 down at half-time, and while they fought back to have the scores level at 3-3 after extra-time, they were knocked out of the FA Cup after losing the penalty shootout.
"The first half was completely unacceptable," Dyche told TNT Sports.
"I let the players know and there are certain individuals that certainly know and they have to look in the mirror.
"But the strangeness of football, some players that came on in the second half were a credit and we went on and looked like a Premier League side.
"You can't do that in the first half, it's completely unacceptable. It's unacceptable to me, but I said you have to look in the mirror because that's unacceptable to the badge as well.
"They all knock on the door and say, 'Why aren't I playing?'. Well, the evidence is quite honestly there for some, not for all."
Dyche also barked: "I could have taken all of them off (at halftime).
"The tempo, the mentality to take the game on was lacking so badly in the first half.
"Slow, methodical, we have done a lot of work on that. There was basically no intent, no real desire to make a difference. Second half, the changes were terrific.
"The facts of the matter are we've got to make changes. They showed their hand and won't be knocking on my door saying, 'why aren't I playing?' again, that's for sure, that first-half group."