Friend and fellow trainer Larry Remmen, who attended the Giants game Monday night at MetLife Stadium in New Jersey with Coughlin, said Coughlin tripped and fell while exiting a taxi outside his home after the game.
"As a result of the fall he had a brain hemorrhage. It was just a freak thing that happened," Remmen said.
Coughlin, 63, died Monday night in Hackensack Medical Center, the New York Daily News reported.
He complied $1.4 million in winnings in his horse racing career before retiring in 2011, and operated Coughlin's Stables at the Meadowlands race track, across the parking lot of the football stadium, the newspaper noted.