The whistle was blown when the ball was in the air so it should have been a replay of the down. Is there an NFL rule that does allow them to consider the pass complete? Is that reviewable?
No 7-2 (m) when an official sounds his whistle erroneously while the ball is still in play, the ball becomes dead immediately
(1) If the ball is in player possession, the team in possession may elect to put the ball in play where it has been declared dead or to replay the down.
(2) If the ball is a loose ball resulting from a fumble, backward pass, or illegal forward pass, the team last in possession may elect to put the ball in play at the spot where possession was lost or to replay the down.
(3) If the ball is a loose ball resulting from a legal forward pass, a free kick, a fair-catch kick, or a scrimmage kick, the ball is returned to the previous spot, and the down is replayed.
(4) If there is a foul by either team during any of the above, penalty enforcement is the same as for fouls during a run, forward pass, kick, fumble, and backward pass. If the team in possession elects to replay the down, the penalty shall be enforced from the previous spot.
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The play isn't reviewable.... "Rule 15 Article 5 Non reviewable plays ....(g) Erroneous Whistle"