In U.S. v. King, the Fourth Circuit in a per curiam opinion for the panel of Judges Luttig, Motz, and Shedd affirmed the guilty plea and convictions of the defendant, based on the written record, of which it was noted in a footnote: "The material includes the supplemental appendix in which the court reporter who transcribed the Rule 11 proceeding stated in an affidavit that she omitted a word in the original transcript. The court reporter stated in her affidavit that defense counsel responded to the court’s question as to whether he had any question about King’s competence, 'I have no doubt, Your Honor.' A corrected transcript page was submitted."
I've wondered about that before - for in-court proceedings, no one gets to fill out an errata sheet on the court reporter's transcript, which is usually remarkably good but not perfect. (I wouldn't take the court reporter's job for any amount of money.)