Flashbacks are commonly used to show something that happened in the past, that in some cases are used to show something that previously happened to someone and shows them remembering it. This is used in the film Kill Bill where the main character would have flashbacks whenever they see a character that they remembered from the start of the film.
You could use this when making film to show some background information about somebody that is related to the film.
Realist films are where films are set on events that could happen in real life- things that are realistic, whereas anti realist films are films that are not realistic and have events in them that would not happen in real life, some anti realist films are Monsters Inc and The hunger games. You would make a realist film as it would help people to relate to it, depending on when it would be set, examples of realist films would be, Saving Private Ryan, and 300.
You would make a non realist films as you don't have to follow a certain event or stick to things that are realistic, you can also make up other aspects of the film to make it more interesting, doing this also gets more attention before release as they are usually very different from other films seen as they have made up a unique plot.
There are two different types of endings, open and closed, open endings are when the film would end with a possibility for a sequel film to follow it, some films with open endings would be; The hobbit: Desolation of Smaug, or inception, where the film ends with the spinning pendant, with the film ending before it falls over or not, leaving people with a memorable moment at the end of the film, thus leaving the audience with an exited reaction.