In 2015, various news outlets revealed that an episode of Homeland included Arabic graffiti protesting the portrayal of Muslims on the popular Showtime series. Some of the phrases written on the set’s walls included “Homeland is racist” and “Homeland is not a show.” The messages were seemingly left on the set without the producers’ knowledge or consent. A group calling themselves “Arabian Street Artists” took credit for the act, saying it was done to air their “political discontent.”

This wasn’t the first time that the background of films and television shows have revealed interesting hidden messages, props, or inside jokes. Here are 10 more examples. 

1. FUTURAMA’S SECRET LANGUAGE

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It’s hard to believe that Homeland and Futurama have anything in common, but it turns out that the latter also includes hidden messages in graffiti and signs. The show contains an alien language, which clever viewers have decoded—allowing them to find messages in the background like “laser tentacle surgery” and “used human probes.”

2. HIEROGLYPHIC R2-D2 AND C-3PO IN RAIDERS OF THE LOST ARK

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In Raiders of the Lost Ark, as Indy lifts a huge rock to uncover the Ark, there’s a pillar featuring hieroglyphics that reference the famous Star Wars characters R2-D2 and C-3PO. There’s a second example later in the same scene, though it’s a little harder to see: on the back wall of the Ark, there’s a hieroglyph of Princess Leia with R2-D2 and C-3PO again.

3. HAN SOLO ON THE FIREFLY

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A 12-inch figurine of Han Solo frozen in carbonite can be seen in many episodes of the science fiction show Firefly. The prop department made this specifically for Nathan Fillion because he’s a huge Star Wars fan. And rumor has it that they used to sneak it into scenes as a joke, without informing the producers and directors.

4. CREW NAMES HIDDEN IN CORONATION STREET

In 2015, some crew members of the British soap opera Coronation Street got into trouble for sneaking their names on to props and sets, including football shirts, newspapers, and resident call buttons. Apparently it went too far when a prop master named Peter Eccleston put his own name on a hardware store. An on-set source told the Mirror, “They think getting their names on TV is a hoot and reckon it’s really funny. But to be honest there are quite a few people wishing for a change at the top to stop this nuisance.”

5. THE RECURRING PROP NEWSPAPER

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Prop masters have inside jokes that go way beyond putting names on a hardware store, though. There is one prop newspaper that has been spotted in a ridiculous number of films and television shows. You can see it in Angel, No Country for Old Men, Everybody Hates Chris, Desperate Housewives, Modern Family, and many other titles. The paper is from Earl Hays Press, a newspaper prop company in Sun Valley, California, and use of the newspaper has become a sort of inside joke within Hollywood—plus, it’s cheaper to recycle.

6. THE GROSS RESTAURANT NAME IN ANCHORMAN

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In Anchorman: The Legend of Ron Burgundy, Veronica Corningstone (Christina Applegate) visits a Mexican food restaurant with a group of her fellow female coworkers. The restaurant’s sign says its name is “Escupimos en su Alimento.” Translated into English, that means “We spit in your food.”

7. THE ACCURATE, AND SOMETIMES HUMOROUS, WHITEBOARD IN THE BIG BANG THEORY

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CBS has a physics professor on the set of The Big Bang Theory to proofread and fact-check the scripts. In addition to making sure everything is scientifically accurate, he sometimes adds some humor to the whiteboard that sits in Leonard and Sheldon’s apartment. For instance, in the episode “The Jiminy Conjecture,” two of the characters get into an argument about a cricket. In the background, the whiteboard features Dolbear’s law, a formula that explains the relationship between temperature and the rate at which crickets chirp. The information on the board doesn’t get referenced much; it’s mostly for science enthusiasts to enjoy.

8. MAGNA DOODLE ART ON FRIENDS

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Beginning in season three, a Magna Doodle toy hung on Joey and Chandler’s door in Friends. At a certain point, a man on the electric crew began changing the drawing on the magnetic surface for each episode. Sometimes the message relatesd to the episode. For instance, in “The One with the Cat,” the apartment gets robbed, and the Magna Doodle displays the message, “Thanks for all your stuff.” A couple episodes later, Chandler gets a manicure. The Magna Doodle reads, “Nice nails, Chandler!”

9. TYLER DURDEN’S FACEBOOK PAGE IN THE SOCIAL NETWORK

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David Fincher directed both Fight Club and The Social Network. In the latter, he referenced an iconic character from his earlier film: Tyler Durden. At one point, Mark Zuckerberg is on his computer, working on Facebook. The words “Tyler Durden’s Photos” are briefly visible.

10. LOST PAINTING IN STUART LITTLE

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This is less of a hidden message than an (unintentionally) hidden object. In the 1999 film Stuart Little, the main characters are an affluent Manhattan family who happen to own a lot of nice paintings. In 2009, an art historian named Gergely Barki was watching the film with his daughter when he noticed a painting by Róbert Berény in the background. That particular painting had been missing since 1928 and was worth around a quarter of a million dollars. Barki eventually got in touch with an assistant set designer for the movie, who had bought the piece at an antique store in Pasadena for just $500. And the painting was returned.