The Giants are under NFL investigation for walkie-talkie use during game against the Cowboys

The NFL is investigating whether the New York Giants violated league rules against the Dallas Cowboys on Sunday night when head coach Ben McAdoo was forced to use a walkie-talkie to communicate with Eli Manning.

Early in the fourth quarter, the radio transmitter in Manning's helmet stopped working, so McAdoo started to use a walkie-talkie to give his quarterback plays. Under NFL rules, communication between the sideline and the quarterback must stop with 15 seconds left on the play clock; McAdoo's use of a walkie-talkie makes it hard to know for certain whether the Giants violated this.

According to the New York Post, the Cowboys lodged an official complaint following the game. At that point, the league had already started to look into it.

Manning's helmet radio cut out earlier in the game, too, which forced him to run back and forth between the sideline to get the play.

"I just wasn't getting anything, so I had to run to the sideline to get the plays," Manning said. "Four plays maybe, we don't have signals for stuff. It happened to be all run plays. If it's pass plays, [backup quarterback Ryan] Nassib or somebody could signal them to me. I had to run to the sideline, sometimes he was giving it to Odell [Beckham Jr.] right there, and Odell would run to me and get the play in. Like high school."

Manning added that he didn't know whether he and McAdoo had violated any rules because of the walkie-talkie.

"I don't know if we did or didn't [break the rules] or what happened there," Manning said.

Ultimately, this shouldn't become a major controversy. If the league does find that the Giants didn't comply with the rule, it's hard to imagine anything more than a fine.