From 1969 through 1989, a span of 21 MLB seasons, the Cleveland Indians finished behind the New York Yankees in the AL East. In the 50 years since divisions came to baseball, only one team has continuously trailed any other one team for longer than that: the Indians, who also finished behind the Red Sox for 23 consecutive seasons from 1969 through 1991. By April 1989, when Major League debuted in theaters, Cleveland had been bad for a very long time.

That part of the film wasn’t fiction. The ending, however, was: At the climax of the movie, Cleveland wins a one-game playoff with the Yankees to take the AL East title, while in real life the 1989 team finished sixth, behind the Yankees yet again. In Major League, which celebrated its 30th anniversary on Sunday, the team starts the season slow but gradually jells in the clubhouse and begins to play a more fundamentally sound brand of baseball that leads to a torrid stretch run. As a close inspection reveals, though, the on-screen squad made an easy-to-miss mistake in the movie’s final few minutes that may have helped it triumph in dramatic fashion. In the late innings of their victory in the tiebreaker, the Indians batted out of turn, and that misstep altered everything.

Let’s retrace some of the steps that took Cleveland’s lineup to its walk-off one-run win in the bottom of the ninth. For the first several innings, we see only snippets of action: right fielder Pedro Cerrano whiffing on a curveball in the bottom of the third, center fielder Willie Mays Hayes popping up for the final out of the fourth, and Cerrano swinging through another curve for strike three in an unspecified subsequent inning. In the top of the seventh, the Yankees’ left-handed Don Mattingly lookalike, Burton, breaks a scoreless tie by going deep against aged righty Eddie Harris, who would have been pulled earlier if manager Lou Brown had been more mindful of the times-through-the-order effect. (In fairness to Brown, the Indians’ staff seems to consist of two pitchers.) That dinger gives the Yankees a 2-0 edge heading into the bottom of the seventh.

Cleveland catcher Jake Taylor bats in the bottom of the inning. Based on Harry Doyle’s play-by-play and the glimpses we get of the field, we know that there’s one out and nobody on. Taylor grounds out to short for the second out of the inning, plunging Cleveland’s win expectancy below 15 percent in a real-world scenario.

That brings up third baseman Roger Dorn, with Cerrano on deck. Dorn singles to left, and Cerrano, who rejects Jobu after going down 0-2, homers to left and carries the bat all the way around the bases (which is unorthodox, but not illegal) en route to tying the game.

Cerrano’s big blow is the last plate appearance we see until the top of the ninth, when Harris (who’s still in the game!) allows a two-out double to another lefty with one runner already on first. That runner, Marks—who somehow doesn’t score on a ball that one-hops the wall even though he runs on contact, making him the hidden goat of the game—stops at third, and Harris walks the bases loaded, setting up Ricky Vaughn’s showdown with Clu Haywood. You know what happens next.

With one out in the bottom of the inning, Cleveland left fielder Tomlinson flies out to the top of the wall in right, and the Yankees’ skipper summons his own relief ace, Duke Temple, to face Hayes. Hayes beats out a chopper to short, which brings Taylor to the plate. After Hayes steals second, Taylor dekes the defense by pretending to call his shot, then slaps a swinging bunt to short. He beats the throw to the bag, and Hayes comes around to score. Cleveland wins. The Yankees lose. The streak is over.

Except—well, wait a minute. Hayes and Taylor shouldn’t have hit when they did.

We can’t determine the entire Indians lineup in the one-game playoff, but based on what we see, we can ascertain the order of five of the nine hitters:

1. Hayes

2. Taylor

3. Dorn

4. Cerrano

5. ?

6. ?

7. ?

8. ?

9. Tomlinson

Now, we can’t say for certain that Hayes is leading off, although it seems extremely likely in light of the type of hitter he is. Regardless, we know who hits before and after him. We also know that there are five outs unaccounted for between Cerrano’s dinger with two outs in the seventh and Tomlinson’s fly with one out in the ninth. Yet there are only four batters between Cerrano and Tomlinson. (We know that the Indians didn’t turn over the lineup between Cerrano’s homer and Tomlinson’s flyout, because the team didn’t score.) If no one reached base after Cerrano, then Tomlinson should have led off the ninth rather than coming up second. And if one batter or more reached base after Cerrano, then Hayes or someone hitting behind him should have been the first batter up in the ninth.

The only possible explanation is that Cleveland batted out of order, skipping a hitter between Cerrano and Tomlinson in the seventh, eighth, or ninth inning. The rules governing batting out of turn—which occurred at least three times during the actual 1989 season—are kind of complicated, but the onus is on the defensive team to catch the offensive team’s mistake. Presumably, the Yankees of Major League failed to notice or weren’t bothered by Cleveland’s infraction and neglected to appeal to the umpires before the next plate appearance began. Thus, the Indians bypassed one of the hitters after their cleanup man and fast-forwarded to the top of the order.

If Cleveland hadn’t batted out of order, then Hayes couldn’t have started a dramatic two-out rally in the ninth. The team might have won anyway, but it wouldn’t have won in that way. Major League’s Hollywood ending depends on an unseen, subtle mistake.

Some might be inclined to pin that mistake on the moviemakers. And sure, Major League takes some liberties with real life; for instance, we might be hard-pressed to summon an in-universe explanation for the fact that the film’s New York–Cleveland face-off takes place in Milwaukee County Stadium, which was then the home of the division-rival Brewers. I prefer to think, though, that the unconventional underdogs simply stumbled into success one more time. In the movie, the Indians succeeded despite being designed to do nothing right. It’s only appropriate that they would seal their unlikely win with one last screwup.

Thanks to Creg Stephenson for spotting Cleveland’s lineup snafu.