Gyllenhaal had to act in a scene with the slippery co-stars because director Denis Villeneuve refused to add the snakes using computer graphics - and he reveals it was difficult rounding them all up.
He tells Wenn, "Everything was done in a controlled way but ultimately there was risk in it and he (Villeneuve) wanted it to be real. The snakes were real and in every single shot they were all around. We had to go searching in the walls of the house after we finished shooting in that house to make sure the snakes hadn't crawled up inside there."
And he admits he was terrified in every scene with the slithering critters: "The snakes were no fun but what was really funny was watching Denis have no fear of them, which was so strange. He'd walk around with seven or 10 snakes and I'd be like, 'How are you not afraid of these snakes?' while I was pretending I wasn't afraid of them. I'm definitely not gonna admit that next to Hugh Jackman! Then Denis would say, 'My son loves snakes. We have snakes everywhere'."