Usually, in short films, the number of main characters is around 1 or 2 due to the short nature of these films. Because short films are only a couple of minutes long, it is not possible to create deep back stories for many characters so the main character count is usually very small.
These are the two main and only characters in 2 AM: The smiling man. The plot to this film is very simple with minimal dialogue and no complex story line.
A typical short film rages between 5 minutes to 10 minutes long- this length is considered short. Any longer and it would be considered an episode as they are feature length. Because of the short nature of these films the story is usually shallow with minimal problems.
Short films usually take place in everyday situations and places. This is done so that it is easier for the audience to relate and no time is wasted trying to explain the setting or events that are happening. eg. Someone waking up and getting ready is an everyday activity which everyone is used to, briefly showing this will immediately idicate to the audience what is going on without showing the lengthy process, however, if the short film was about an alien apocolypse this would have to be explained somehow before or during the action takes place which could be too confusing for a 5-10 minute film.
Because the events that take place are usually ordinary things, short films often include a twist which keeps the audience captivated. For example, 'The Black Hole' is a short film showing a normal day in an office until there is a twist that the man walk through walls etc by walking through a black cirlce on some paper.
Situations and twists
Because most short films are made by independent companies, the budget is often very small or nothing at all. Very little short films use CGI etc. because of this and have very simplistic editing techniques. A way that short film producers keep their budget down is by using few free loactions and getting volunteer actors.