Jake Gyllenhaal believes in aliens

He told the New York Daily News: "I believe there's so much yet to be explored. I think absolutely, there is no doubt in my mind — whether or not they're friendly or already here — I think there's a lot left to explore."

Meanwhile, Jake and his co-star Ryan Reynolds, 40, have spoken about the lasting bromance they formed on set.

Speaking to Access Hollywood, Ryan said: "You do these films and get to work with really amazing people, really talented people and you think 'oh I'm going to hang out with these people afterward and see them again. You don't most of the time because you go on living your life. But with this guy, we've stayed friends. That's a lucky thing. It doesn't always happen."

"I loved working with this guy. I loved spending time with this guy. It's not often you get this experience."

And Jake admitted he was thrilled to meet someone who is so "genuine".

He said: "We sort of grew up in this business together without knowing each other until very recently. It's hard in a business where ... a lot of times we're pretending to get closer to the truth and to find somebody who you feel is genuine. I feel that way about him, so we're friends."

Although the movie, which has been compared to Ridley Scott's 'Alien', has a number of terrifying scenes, Jake revealed the pair were laughing constantly.

He said: "We had really scary situations in the movie and scenes that were really tense, but we were laughing constantly and it was so much fun."