What began as director George Miller's ambitious action film about a solitary cop (Mel Gibson) on a mission to take down a violent biker gang has evolved into a post-apocalyptic sensory overload of a franchise that now has four films to its credit—Mad Max (1979), The Road Warrior (1981), Mad Max Beyond Thunderdome (1985), and Mad Max: Fury Road (2015)—and additional sequels in the works. So let's obsess over Miller’s masterpieces even more with these 11 things you might not know about the franchise.

1. Director George Miller worked as a doctor to raise money for Mad Max.

Mel Gibson in Mad Max (1979). Metro-Goldwyn-Mayer Studios Inc.

Since the film only had a budget of $350,000, Miller scraped together extra money as an emergency room doctor to keep the movie going. “It was very low budget and we ran out of money for editing and post-production, so I spent a year editing the film by myself in our kitchen, while Byron Kennedy did the sound,” Miller told CraveOnline. “And then working as an emergency doctor on the weekends to earn money to keep going. I’d got my best friend, and friends of friends of friends of his, and Byron ditto, and I thought, ‘Oh my God, we made a film and it won’t cut together and we’re going to lose all their money.’”

Miller’s medical training is all over the film: Max Rockatansky is named after physician Carl von Rokitansky, a pathologist who created the Rokitansky procedure, a method for removing organs in an autopsy.

2. Mel Gibson went to the Mad Max audition to accompany his friend, not for the part.

Gibson was black and blue after a recent brawl with “half a rugby team” when his friend asked him to drop him off at his Mad Max audition. Because the agency was also casting “freaks,” they took pictures of Gibson, who was simply waiting around, and asked him to come back when he healed. When he did, Miller gave him the role on the spot. In a clip for Scream Factory, Gibson recalled the moment: “It was real weird. [Miller] said, ‘Can you memorize this?’ and it was like two pages of dialogue with a big speech and stuff. I was like, ‘Yeah, sure.’ I went into the other room and just got a gist of what it was and I came out and just ad-libbed what I could remember. I guess they bought it.”

3. George Miller paid Mad Max crew members in beer.

With barely enough money to finish the original film, Miller offered to pay ambulance drivers, a tractor driver, and some of the bikers on set with “slabs” (Australian for a case of 24 cans) of beer, according to The Guardian.

4. Real-life motorcycle club the Vigilanties played Toecutter’s gang for Mad Max.

Forget the money required to train stuntmen; Miller and crew hired real bikers to professionally ride into production. In an interview with Motorcyclist Online, actor Tim Burns said about working with them: “[The Vigilanties] all wanted to ride the bikes as fast as possible, as often as possible, by their nature. Their riding was individually and collectively superb.” Additionally, stuntman Dale Bensch, a member of The Vigilanties, recalled seeing the ad for the shoot at a local bike shop, and took a moment to clarify a mishap that had happened during production. Bensch said, “There’s an urban myth that a stuntman was killed, and that was me. The scariest thing was dropping the bike on that bridge. They took the speedo and tach off because they didn’t want to damage more than they had to. They wet the surface to make it easier, but I hung onto the bike too long and it flipped me over with it; that’s why it looked bad. But it’s a famous scene, so it worked out all right!”

5. Mad Max 2: The Road Warrior was inspired by the oil crises of the 1970s.

During an interview with The Daily Beast, Miller discussed the making of The Road Warrior. Of its inspiration, he said, “I’d lived in a very lovely and sedate city in Melbourne, and during OPEC and the extreme oil crisis—where the only people who could get any gas were emergency workers, firemen, hospital staff, and police—it took 10 days in this really peaceful city for the first shot to be fired, so I thought, ‘What if this happened over 10 years?’”

6. Mel Gibson only had 16 lines of dialogue in The Road Warrior.

Upon Fury Road’s release in 2015, social media lit up with complaints that Tom Hardy was underutilized, only there to grunt and utter a couple of one-liners. But just to remind you, in Mad Max 2, Mel Gibson only has 16 lines of dialogue in The Road Warrior.

On his use of sparse dialogue, Miller told The New York Times, “Hitchcock had this wonderful saying: ‘I try to make films where they don’t have to read the subtitles in Japan.’ And that was what I tried to do in Mad Max 1, and I’m still trying to do that three decades later with Fury Road.”

7. Mel Gibson says The Road Warrior is his favorite movie in the original trilogy.

Once upon a time Mel Gibson enthusiastically spoke about Beyond Thunderdome, telling Rolling Stone, "[The films are] a sort of cinematic equivalent to rock music. It's something to do with the nihilistic sentiments of the music of the ’80s—which can't continue. I say, let's get back to romanticism. And this film [Thunderdome] is actually doing that. It's using that nihilism as a vehicle, I think, to get back to romance.”

Years later, he told Playboy what he really thought of the films, namely that The Road Warrior was his favorite. “It still holds up because it’s so basic,” Gibson said. “It’s about energy—it didn’t spare anyone: people flying under wheels, a girl gets it, a dog gets it, everybody gets it. It was the first Mad Max, but done better. The third one didn’t work at all.”

8. Beyond Thunderdome was inspired by Lord Of The Flies.

Mel Gibson and Tina Turner in Mad Max Beyond Thunderdome (1985). Warner Home Video

Even though Miller and his producers were on the fence about a third Mad Max, they couldn’t help but give in. "George was sitting and talking to me about … quantum mechanics, I think," Miller’s co-writer Terry Hayes recalled to Rolling Stone. "The theory of the oscillating universe. You could say he's got a broad range of interests. And I said something about ‘Well, if there was ever a Mad Max III ...' And he said, 'Well, if there was ...'"

In a 1985 interview with Time Out, Miller recalled the story himself. “We were talking one day and Terry Hayes started talking about mythology and how where people are short on knowledge, they tend to be very big on belief. In other words, they take a few fragments of knowledge and, if you take like the Aboriginal tribes of Australia, they just take simple empirical information and using those little bits of the jigsaw construct very elaborate mythological beliefs, which explain the whole universe,” Miller said. “Terry was saying if you had a tribe of kids after the apocalypse who had only a few fragments of knowledge, [they would construct] a mythological belief as to what was before. And what would happen if Max or someone like that [came in] ... and it kicked off the idea of kids who were Lord of the Flies-type kids, and that led to this story.”

9. Tina Turner was cast in Beyond Thunderdome because of her positive persona.

According to Rolling Stone, Tina Turner beat out Jane Fonda and Lindsay Wagner for the role of Aunty Entity. On her casting, Miller told Time Out, “One of the main reasons we cast Tina Turner is that she’s perceived as being a fairly positive persona. You don’t think of Tina Turner as someone dark. You think of the core of Tina Turner being basically a positive thing. And that’s what we wanted. We felt that she might be more tragic in that sense. But more importantly [when] we actually wrote the character, as a shorthand way of describing the character we said someone ‘like Tina Turner’—without even thinking of casting her. We wanted a woman ... we wanted someone who had a lot of power, charisma, someone who would hold a place like that together—or build it in the first place. And we wanted someone who was a survivor.”

10. Mad Max characters’ names hint at their backstories.

One of the most peculiar quirks of Miller’s franchise has to be his bizarre character names. In an interview with Fandango, Miller explained exactly how he comes up with them: “One of the things is that everything in the story has to have some sort of underlying backstory. Not just every character, but every vehicle, every weapon, every costume—and the same with the language. So [the concept] was always found objects, repurposed. Immortan Joe is a slight adjustment to the word 'immortal.' The character Nux says 'mcfeasting' instead of using the word 'feasting,’” Miller explained, adding that his favorite name of all is Fury Road’s The Dag (played by Abbey Lee). “In Australia, the dag is sort of a goofball-type.”

11. George Miller is a proud feminist.

George Miller poses with the Feature Film Nomination Plaque for Mad Max: Fury Road during the 68th annual Directors Guild Of America Awards in 2016. Frederick M. Brown/Getty Images

Perhaps evidenced by Charlize Theron’s scene-stealing role as Imperator Furiosa, Miller is a proud, outspoken feminist. He told Vanity Fair, “I’ve gone from being very male dominant to being surrounded by magnificent women. I can’t help but be a feminist.” That female influence even stretched behind the scenes, with Miller asking his wife Margaret Sixel to edit Fury Road. “I said, ‘You have to edit this movie, because it won’t look like every other action movie,” Miller recalled. Moreover, feminist activist Eve Ensler also consulted on the film to offer, according to Ensler herself, “perspective on violence against women around the world, particularly in war zones.”