On Sunday, Peyton Manning did something no one has ever done: He threw for more passing yards in a single season than any quarterback before him. And he broke the record by the slimmest of margins — one yard.

But that could all be taken away as the statisticians are now reviewing one play in particular that could erase the record.

It all hinges on a pass from Manning to receiver Eric Decker in the closing minutes of the first quarter of the game against Oakland. On that play, Manning threw a quick pass out to Decker in the left flat. It went for seven yards. But now the question is whether the ball was actually thrown backwards and not completed forwards. That tiny distinction would turn the completion into technically a lateral and a run.

In determining such plays, the important factors are where the ball is released (not where Manning ends up), and where Decker actually catches the pass.

And if you view the completion by using screen shots, it does look like Manning releases the ball from the 49-yard line, and Decker appears to catch it at the 48 (we’ve drawn some lines to help you visualize):

Peyton Mannings passing yards record under review

(Source: NFL.com screen shot/TheBlaze)

Peyton Mannings passing yards record under review

(Source: NFL.com screen shot/TheBlaze)

Peyton Mannings passing yards record under review

(Source: NFL.com screen shot/TheBlaze)

You can watch the play over at Yahoo.

Now, Yahoo’s Frank Schwab notes that TV cameras can create some optical illusions, so there is a chance the play stands. But Elias Sports Bureau, which keeps official stats for the NFL, is taking a look.

Here’s the kicker, though: The Broncos pulled Manning at halftime, likely knowing he had broken the passing mark. So the stat correction could be even more painful considering the move and the slim margin.

But Manning has played down the record, indicating it might not be that big of deal. He had already broken the record for most touchdowns in a season and when asked about the yardage record after the game, he didn’t have much comment.

“I don’t really have much to say about it, to tell you the truth,” he said.

Manning had racked up 5,477 yards this season, surpassing Drew Brees and his 2011 record. If the play is re-categorized, he’d fall to 5,470 yards and number two all time. Still, as ESPN notes, a career best.

(H/T: Deadspin)