Millwall took the lead in the first-half after a defensive mix-up, but Palace responded after the restart.
“It was a crazy experience,” Mitchell told Palace TV. “We could see by the fans, they made it hard to play. I feel like we had loads of possession in the first-half but it was just about our final play, our tempo on the ball.
“In the second-half, we started that well and you could see by the two goals. All 11 of us on the pitch, we’re going to make mistakes. It’s just about rallying together and helping each other through the mistake.
“Sometimes someone’s head might go down, so it’s just about being a good teammate and helping them get through it.”
Michael Olise was devastating going forwards in the second-half, but having faced him in training all season, Mitchell was not surprised.
“He’s a top player,” Mitchell said. “You can see any time he comes on he causes problems and scores goals. I just tackle everything [in training].
“He might say otherwise, but you know the truth!”
After playing much of last season behind closed doors, Mitchell is thriving in the difficult atmospheres presented by packed stadiums.
“It’s definitely enjoyable – particularly at home,” he explained. “Playing in front of our fans is brilliant, but it is still hard at the same time. It’s much better than last season in terms of atmosphere.
“You hear it [the Millwall fans] but you just try and block it out. You don’t hear any good stuff, so you just try and block it out.
“The aim was to get through to the next round. I don’t mind [who we draw], anyone to be fair – I just want to have a good cup run.”