NEW YORK — (CNN) At the end of the first quarter of the Thanksgiving Day Eagles-Lions football game, there was a startling commercial for “Concussion.”

It was the first time an ad for the film about football-related brain trauma has appeared during an NFL game.

“Concussion,” coming to theaters on Christmas Day, has been described by Vanity Fair as “the film the NFL doesn’t want you to see.”

A spokeswoman for the film’s distributor, Sony Pictures, said that “quite a few spots” are running during Thanksgiving games, including the NFL’s Panthers-Cowboys game and the college football Texas-Texas Tech match-up.

There had been speculation recently that the NFL and its television partners would not want ads for the film to run during games.

But Sports Illustrated reported earlier this month that all the networks except for the league-owned NFL Network had decided to accept the ads. (A blackout would probably have garnered the film even more attention.)

Sony describes the film this way: “A dramatic thriller based on the incredible true David vs. Goliath story of American immigrant Dr. Bennet Omalu, the brilliant forensic neuropathologist who made the first discovery of CTE, a football-related brain trauma, in a pro player and fought for the truth to be known. Omalu’s emotional quest puts him at dangerous odds with one of the most powerful institutions in the world.”

The movie trailer debuted several months ago, and now the marketing campaign is ramping up.

Ads for the film also ran in pre-game and post-game shows on ESPN’s “Monday Night Football” earlier this week.

But the ads on Thursday, during game play, created more of a stir, at least judging by the reactions on Twitter.

Patrick Goldstein, a longtime movie critic and columnist, tweeted during the Lions game, “When it comes to Thanksgiving cognitive dissonance, nothing quite like seeing dramatic Concussion ad in middle of NFL game.”

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