Actors are advised to never work with children or animals and fornew film that may have been worth sticking to.
Beast is a survival epic which follows a recently widowed husband (Idris) as he returns to the game reserve in South Africa, where he met his late wife, with his two children.
But the long-planned trip takes a turn for the word when a man-hunting lion begins attacking them and devouring anyone in its path, pushing the family’s resilience to the limit.
And it seemed life imitated art when director took a leap of faith and decided to bring a lion on set.
At one point the big cat managed to escape and was roaming around freely, although no one was harmed.
Baltasar told Total Film: ‘I’m not sure I’m allowed to say this, but [the lion] got out at one point, and there was a little bit of panic on set!’
The lion came about because Baltasar asked fellow director Alejandro González Iñárritu, who was behind The Revenant, how to capture the creature realistically on CGI.
Though a little unorthodox, Alejandro’s response was to source a real lion and note down how the light fell on its fur while on set.
Baltasar explained: ‘So I went to the studio and said, ‘Can I have a lion on set?’ The answer, improbably, was “yes”.’
Idris, 49, overhauled his diet to get in shape for Beast, with his personal chef revealing how the actor got fighting fit for the role.
, King The Chef revealed he was flown out to South Africa to feed the actor as he filmed intensive 12-hour days.
He said: ‘That filming period was three months so we altered his diet a few times.
‘I had him on a pescatarian diet for that, we introduced a lot of protein more than carb-rich [food] just because he wanted to keep lean – not too lean – just enough to be able to look the part.
