Papale, who made the Eagles' roster after a public tryout held by first-year Coach Dick Vermeil, ended up playing on special teams for three seasons.
Four years earlier, Mul-Key had made the Washington Redskins' roster after a public tryout and played on special teams for three seasons.
Mul-Key and Papale had impressed coaches at their respective tryouts with their speed. They were timed in 4.5 seconds for 40 yards.
There were some differences, however.
Papale was 30 when he made the Eagles. Mul-Key was younger. Papale had attended college, St. Joseph's in Philadelphia, where he'd run track. Mul-Key had not attended college.
Papale, as a backup wide receiver, caught only one pass for 15 yards in his three seasons with the Eagles. But he was named special teams captain in 1977.
Mul-Key, as a backup running back, had 33 carries for 155 yards in 1972, his rookie season. He was used mainly as a kick returner, however, and he made the Pro Bowl in that position after the 1973 season.
Papale has been highly visible lately, doing television, radio and newspaper interviews to promote the movie.
Efforts to locate Mul-Key through the Redskins, the NFL Players Assn., the NFL Alumni Assn. and computer searches were not successful.
Billy Kilmer, the Redskins' starting quarterback then, said, "Herb didn't have real good football skills, but he was fast. And he played with a lot of heart."
Kilmer said he remembered that the first time Mul-Key ever touched the ball in a game -- an exhibition against Buffalo -- he went about 80 yards for a touchdown on a punt return.
"He was a nice, quiet kid," Kilmer said.
One of the first things Vermeil did after becoming coach of the Eagles in 1976 was to announce that a public tryout would be held. It was open to anyone who thought he could play in the NFL.
Sports-crazy Philadelphia had become disenchanted with the Eagles, and Vermeil thought this was one way to generate interest in the team.
But, considering that the Redskins had done the same thing four years earlier, the idea obviously wasn't original.
Reached at his home on his 114-acre ranch in Pennsylvania's Chester County about 45 miles west of Philadelphia, Vermeil, who at 69 retired as coach of the Kansas City Chiefs after last season, said he borrowed the idea for the tryout from George Allen.
Vermeil was on Allen's staff with the Los Angeles Rams in 1969 as the NFL's first special teams coach. He left in 1970 to become offensive line coach for UCLA, but returned to the Rams a year later, when UCLA's Tommy Prothro became the coach.
Vermeil returned to UCLA in 1974 as head coach and the next season the Bruins, led by quarterback John Sciarra, upset No. 1-ranked Ohio State, 23-10, in the Rose Bowl game on Jan. 1, 1976.
Within days of that victory, Vermeil was named coach of the Eagles.
Vermeil was aware that Allen had held a public tryout after going from the Rams to the Redskins in 1971. More than 300 young men showed up for that tryout at Georgetown University. Only one of the tryouts, Otis Sistrunk, was invited to training camp. But he was cut after one week.
Sistrunk, however, went on to become a starting defensive lineman for the Oakland Raiders the next season, and stuck for seven seasons.
Sistrunk, who did not attend college, might be best remembered for a Monday night game in 1973 when, with steam coming off his bald head in the cold air, ABC announcer Alex Karras said he must have played for the "University of Mars."
In 1972, Allen's second public tryout drew 385 hopefuls. This time, Mul-Key was the only one invited to training camp. And unlike Sistrunk the year before, Mul-Key made the team.
"I think George wanted to prove he could take a kid off the street and make him a good football player," Kilmer said.
Vermeil said he never really thought of Papale's story becoming a major motion picture until ESPN ran an NFL Films feature on Papale five years ago, marking the 25th anniversary of Papale's making the team.
That's also when the makers of the film took notice, and the project began about a year later.
Vermeil attended the premiere in New York on Wednesday night and said he liked the movie.
"It's a down-home, warm story -- a good story," Vermeil said Thursday by phone. "One thing my wife and I liked was that there are no swear words in the movie."
As with any true story, Hollywood, for whatever reason, always feels the need to tinker with the facts, and that is the case with "Invincible" as well.
"It's not a documentary," Vermeil said.
Among other things, the final scene in the movie is only somewhat similar to what happened. And NFL Films footage from a real game against the New York Giants that is shown after the conclusion of the movie is misleading.
In the movie, Papale, playing his first home game for the Eagles, is shown causing a fumble on a punt, scooping it up and running nearly the length of the field for a game-winning touchdown as time runs out.
Then the actual footage shows the real Papale picking up a fumble and running a few yards into the end zone and celebrating.
What is not shown is that the fumble, which occurred in the middle of the fourth quarter, was ruled a muff and could not be advanced. The Eagles scored a few plays later, but it was not a winning touchdown. The Eagles led, 13-0, at the time.
To Hollywood, those are minor details.
Vermeil, however, said he was impressed not only with the job actor Mark Wahlberg did portraying Papale, but also his football skills. And he thought actor Greg Kinnear captured him as a 37-year-old coach pretty well.
"I guess that's the way I act," he said. "To be honest, I don't know how I act. You never see yourself act."