Doyle, on loan from Birmingham City, let Jermain Defoe's free-kick squirm through his fingers and over the line to hand us a 1-0 lead just before the break of the fifth round tie at the Lane.
However, he responded with key saves from Defoe and Mido to earn Forest a replay after Gareth Taylor's equaliser on 55 minutes.
Indeed, it needed a great late save from Paul Robinson to deny Kris Commons from close range minutes before the final whistle.
"You do feel for him," said Megson. "Unfortunately that was the softest shot he had all afternoon and he just took his eye off it. It was an awful error.
"But there is no getting away from it that after that he showed a strength of character you might not expect in a 19-year-old.
"He played ever so well. The most pleasing thing was that he came out and took a cross 17 metres out with five minutes to go. It would have been easy to expect him to not come for it.
"To make your debut under those conditions isn't ideal. But he is not coming into a team that is flying, he has come into a team that has let in 45 goals. Nobody had go at him or particularly mentioned it at half-time.
"He made a mistake but the way he got on with it was very impressive."
Megson was happy his side deserved the draw and felt they might have even snatched a win.
"In the quality of chances we had, we could have won," he added.
"That has been the story of my season at Forest over the last few weeks. We don't turn enough chances into goals, hence we are where we are."
Forest boss Gary Megson praised the character of his debutant keeper Colin Doyle after he made such a big mistake for our goal in Sunday's 1-1 draw.