What does this mean: "Mismatch at byte 1690/sector 1597912. Verification failed"

I got this message after popcorn burned a disk and about 3/4 of the way through the verification process.

It could be a bad disc. One thing to try is choosing Save as Disc Image from the File menu instead of clicking the burn button. Then use the Image File setting to burn the disc image to DVD. This sometimes works better.