She explains, "I get to his house and they told me it (audition) would be on Skype (internet video calling programme), which was so strange because his assistant was there, his casting director was there and he's there on a laptop.
"I just went for it and I actually found out later that day that I got the movie and I was off to shoot two weeks later. It was the fastest job I've ever gotten."
But before filming could start, Roberts had to be fitted with platform boots to make her character appear taller.
She tells WENN, "I'm really small compared to everyone else in the movie because I'm short, so I was literally running around in seven inch boots the whole movie, so I could be up to the right height to everyone else (sic). I almost ate it (tripped over) a couple of times. There was a moment where I was running up some stairs late at night and I almost really took a fall."