John Krasinski "acted out" the creatures in 'A Quiet Place Part II' to put his cast at ease.
Cillian Murphy - who has joined the cast for the sequel as the mysterious Emmett - praised the movie's "committed director" for the lengths he went to in order to stop the actors from always working with both CGI and green screen.
Cillian said: "The way John runs the set, it never feels like you're working with a green screen. All the locations were real. There was very little studio work, certainly for me.
"We shot in Buffalo in New York. On extraordinary sets. We didn't have to 'pretend act' like we would on a green screen.
"Sometimes John would even act out the creatures while on set so we would know where the creatures would be.
"John is incredibly energetic, he transmits this enthusiasm.
"He's one of the most committed directors I've ever worked with.
"I just felt we were in an extension to that world."
And Cillian admitted having seen the first movie was a big help.
He told SciFiNow magazine: "Also because I'd seen the first film I knew what [the creatures] looked like, how they moved.
"The way their bodies work and the way their hearing works. I was well aware of that, so it was never an issue."
The 'Peaky Blinders' star was thrilled to be asked to appear in the sequel because he'd been such a big fan of the first movie, he'd written an email of praise to John - but "chickened out" of sending it.
He said: "I was so impressed with the first movie that I wrote an email to John to tell him that but I chickened out in the end and didn't send it.
"Luckily, he was aware of my work and a year later he send me an email asking me to be in the sequel, so it worked out."
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