According to the league's Last Two Minute Report, Sixers forward Tobias Harris grabbed Allen, preventing him from rolling from his screen and releasing to the basket sooner.
If Harris hadn't grabbed Allen, he might've had enough time to dunk the ball and tie the game. Instead, the extra second allowed him to be corralled by three defenders, and he eventually turned the ball over, preventing the Nets from attempting a potential game-tying -- or winning -- shot in the final seconds.
Harris was eventually fouled and sank two free throws with 4.9 seconds remaining to seal the 112-108 win for Philadelphia, which gave the Sixers a 3-1 lead in the best-of-seven series.
"So the big point of emphasis this year was the wrapping, wrapping the player when he rolls to the rim," Nets coach Kenny Atkinson said after Saturday's game. "Judge for yourself if you watch the clip, but there was a clear wrap by Tobias Harris on the roll.
"I am just disappointed. That was a point of emphasis on day one at the coaches' meetings -- that they were going to emphasize that at the beginning of the game, the end of the game and all season. So how that all of a sudden doesn't become a foul on the wrap, I don't understand that."
There was one other missed call, as the league said Nets guard Spencer Dinwiddie should've been called for a carry with 1:45 remaining.
The league also announced Saturday afternoon that Jared Dudley had been fined $25,000 and Jimmy Butler $15,000 for their roles in escalating the fracas that briefly spilled into the stands midway through the third quarter following a hard foul on Allen by Joel Embiid.
Embiid was called for a flagrant foul on the play, which league sources told ESPN would stand as called and not be downgraded retroactively to a common foul. That means Embiid remains with two flagrant foul points, putting him halfway to an automatic one-game suspension, which kicks in when a player reaches four flagrant foul points in the playoffs.
Brooklyn and Philadelphia resume their series Tuesday at Wells Fargo Center in Philadelphia, where the Sixers will try to close out the series.