The scene above, from the classic Ingmar Bergman film The Seventh Seal, has a unique premise. Death—a cloaked figure with a very pale face—has come for Antonius, a knight fresh off the Crusades who just wants to live out his life in peace. Understandably frustrated, Antonius does what any of us would: he challenges Death to a game of chess, with his soul as the prize.

A regular schmo watching this scene picks up on a few things: the terror, the suspense, the artful composition of the shots. A chess aficionado, though, is only looking at one thing. That game board that decides Antonius’s fate? It’s set up totally backwards.

Movies and television shows are full of blunders, some more noticeable than others, and each with their specific guild of victims. Ornithologists fume when British period dramas are overdubbed with American birdsongs. Government employees will tell you that the supposed main White House staffer in Contact has a nonexistent job. Archeologists hate movie shipwrecks, and marine biologists are already mad about the zombie sharks in the upcoming Pirates of the Caribbean installment, which, as cartilaginous fishes, should not have ribs—even ghostly ones.

But these are merely occasional grievances. There’s one group of experts who can barely flip on the television without being exposed to egregious, head-on-desk mistakes: chess players.

A correctly set up chess board, for reference. Staxringold/CC BY-SA 3.0

“There are a ton of chess mistakes in TV and in film,” says Mike Klein, a writer and videographer for Chess.com. While different experts cite different error ratios, from “20 percent” to “much more often than not,” all agree: Hollywood is terrible at chess, even though they really don’t have to be. “There are so many [errors], it’s hard to keep track,” says Grandmaster Ilja Zaragatski, of chess24. “And there are constantly [new ones] coming out.”

Chess errors come in a few different flavors, these experts say. The most common is what we’ll call the Bad Setup. When you set up a chessboard, you’re supposed to orient it so that the square nearest to each player’s right side is light-colored. (There’s even a mnemonic for this—“right is light.”) Next, when you array the pieces, the white queen goes on white, and the black queen goes on black. “When I teach six-year-old girls, I say ‘the queen’s shoes have to match her dress!’” says Klein.

Six-year-olds may get this, but filmmakers often do not. Along with The Seventh Seal, movies that suffer from Bad Setups include Blade Runner, Austin Powers, From Russia with Love, The Shawshank Redemption, and Ace Ventura: When Nature Calls. Shaft and What’s New Pussycat may not have much in common, but they do both feature backwards chessboards.

Slightly less common, and a little more understandable, is the Dramatic Checkmate. This blunder occurs when one opponent surprises another by winning out of nowhere—or, similarly, when some extra-smart character walks by a game in progress and points out a checkmate opportunity the players didn’t spot. (There are a bunch of good last moves and shocked faces in the helpful Checkmate Supercut above.)

While this is understandable from a dramatic standpoint, or even a character-building one, it’s not at all realistic, says Klein. “Two reasonable chess players never get surprised when checkmate happens,” he says. “That would be like a team making a three-pointer, and the other team only then looking at the scoreboard and suddenly realizing they’d lost.” Real players also don’t make a big thing out of winning: “Chess players almost never reveal any emotions,” says Zaragatski. “Being cool is key.”

Peter Doggers of Chess.com notes another Dramatic Checkmate move: the felled king. “Tipping over your king as a way of resigning the game is only done in movies,” he says. (See Mr. Holland’s Opus, in which Jay Thomas slaps his king down after being owned by Richard Dreyfuss). A normal chess player will just go in for a good-game-style handshake. “This falling king thing has somehow become a strong image in cinematography,” he says, “But chess players always think: ‘Oh no, there we go again…’”

Finally, there are the Deep Cuts—those errors that only the most knowledgable and dedicated chess hounds will notice. “Occasionally there is simply an illegal position,” says Klein—in other words, a midgame setup that just doesn’t make sense. In Back to the Future Part III, when Marty McFly loses a chess game to Copernicus the dog, he does so despite an illegal position, and one Season 5 episode of The Office has Jim with both of his bishops on white squares, an impossible orientation in that particular game.

In at least one case, unusual play has sparked decades of academic debate: Experts still argue over whether HAL, the computer in Stanley Kubrick’s 2001: A Space Odyssey, was cheating in his game against astronaut Frank Poole, or whether Kubrick simply made a mistake.

To the experts, such errors seem needless. “It’s like if you were reading something, and you see spelling mistakes,” says the chess historian Bill Wall. Wall has occasionally worked as a film chess consultant. Although most films don’t bother hiring one of those, there are other options: “There are around 6 million chess games easily accessible in online databases,” says Zaragatski.

They aren’t the only ones bothered. Browse over to one of the many forum posts on the topic, and you’ll find people noting down movie titles and scenes as though they’re working on a hit list. “I just wanted to know if I could find some moral internet support after seeing… illegal moves, repeat positions, the knight called a horse, etc.” writes Chess.com user Politicalmusic, beginning one such thread. “I haven’t seen a good chess scene in a non-chess movie since Harry Potter,” gripes user TitanCG.

There are some upsides to being one of the lonely few, says Klein, who admits to pausing most movie chess scenes to try to puzzle them out. “I enjoy being a detective,” he says. Sometimes, what he finds brings a bit more satisfaction: if a knowledgable person set up the board, it could be a puzzle, or a historical reference. He and Doggers both cited a recent Simpsons episode, which guest-starred chess prodigy Magnus Carlsen, as a good example, full of in-jokes and recreations of historically important games. “It’s so cool when the chess part is actually done very well,” says Doggers. “That’s just great.”

And when it’s not—well, most people will think the film is smart because it has chess in it, while a small group is left burdened with the truth.