The Broncos receiver dropped Peyton Manning's pass early in the second half on third down, but officials ruled it complete and Harbaugh didn't challenge, which turned out to be costly as the home side scored on the drive.
"This is the first I've heard of it," Harbaugh told reporters.
"That's something you have to see. It would be nice if NBC would show it, but we didn't have a chance to look at it."
Baltimore conceded the most points in a single game in the history of their franchise in the defeat at Mile High Stadium.