One of the reasons that “The Mousetrap” has been so successful is that people don’t spoil the ending for those who haven’t seen it. “See How They Run,” shows the end of the play without revealing the murderer. Instead, all we see is Richard Attenborough telling the audience that watching their play makes them participants in a murder, and if they were to tell anyone whodunit, they would be subject to legal action. It’s just a fun way of asking the audience not to spoil the ending by making them feel like they’re part of the production.
As important as keeping the identity of the killer a secret is, it wasn’t much of a priority to director Tom George during production. When Screen Rant Plus asked him if he filmed murder scenes multiple times with different actors to keep everyone guessing, he was forced to admit he didn’t really think about it. “Yeah, we were actually probably way too trusting. I just relied on, you know, a cast of 30 or 40 actors and maybe 200 crew to just, like, not tell anyone. Which, with hindsight, was a risk.”
However, he is also of the opinion that the whodunit aspect of the film isn’t the most important element: the characters are. “What these films are most brilliant for, I think, is like taking you on a journey through a cast of characters.”