An unlikely film broke the box office this weekend. Deadpool, the Ryan Reynolds–headliner about a mercenary turned superhero, definitely came out of left field.

“I’ve rarely seen such box office successes in my career,” said Pamela McClintock, a Hollywood Reporter senior film writer.

For one, the final budget for the film was just $58 million. And as of this weekend, the film has made more than $150 million domestically.

McClintock said Deadpool is much different from your average superhero film. With the amount of major cursing and violence in the film, Deadpool is rated R. That rating could have ruled out some audiences, but it actually led to the film becoming a big hit.

Parts of the film were also allegedly leaked online by studio executives and people on the filmmaking team prior to the film’s release — which probably added to the film’s success, according to McClintock.

“Whoever leaked that footage, it really worked,” McClintock said.

The film’s major success is also in part thanks to Ryan Reynolds, who is not just the star of the film, but also a producer. McClintock said Reynolds wasn’t really happy with the way Deadpool was portrayed in the X-Men films. So Reynolds stuck by his version of the movie for more than 10 years until it was finally picked up by Fox studios.