There was never an actual review in the Auburn game. In that game, one of the upfield officials threw the flag and after the crew conferred, either the referee or umpire saw the tip and ruled no foul.

This is exactly why penalties should be reviewable. What's the difference between a defense getting called for a personal foul and the offense picking up 15 yards on a play? There are also several loopholes when it comes to what's reviewable. For example, a ruled interception that looked like an incomplete pass is reviewable, but if it was ruled incomplete, end of story, no review.

My understanding of the rules is:
PI is not reviewable.
Tipped balls are reviewable.
The AU PI last year was not reviewed, it was overturned on the field. Not sure about the UK game this year.