Ruairi Robinson stated that as a first time director, to get to work with a cast of that caliber was amazing. On the casting process, he commented that he "sort of picked cast members that never normally do this kind of film. They all do serious proper movies". He also said that he "liked the idea of putting people who would never normally do Sci-Fi stuff into a Sci-Fi movie, because they are going to take it seriously then and people are going to take them seriously".
Screenwriter Clive Dawson tried to be faithful to the original short story by Sydney J. Bounds, "The Animators". However, in the story, the crew is composed of six men. For the adaptation, Dawson added two new characters and wrote some of them as female characters.
When asked what appealed to her about Last Days on Mars, Romola Garai answered that "it was a science fiction film and, in that way, it was really different from anything I'd done before" and that she "was very attracted to doing something different. It had a great cast attached when I auditioned for it, and a really good director". She added that she loves science fiction and reads a lot of science fiction, so she "was really excited to do something in that genre."