Trying to find a post I made a while ago on Flash Fiction, but gave up because I think I can give you the gist of it, and as it applies to some current short stories I’m reading as well as a recent workshopped story we did in our last Narratives meeting. The post was one listing a few of the comments by writers in either "Flash Fiction" or "Sudden Fiction" to illustrate the point that while a complete story could be told regardless of length, whether it be a novel or a three-pager, the difference was in the details. Compression is essential in the short story, and clever use of language to give the most information in the least amount of words.
In the stories in I’m referencing, one published in Glimmertrain, both are heavy in characters, specifically, giving full names and often a tidbit of information, whether descriptive or involved in a vignette, that do not serve the story but tend to confuse the reader. Readers tend to take any new character introduced in a narrative seriously, thinking that the character will figure into the plot and thus they are willing to get to "know" and hold onto the character. After sticking all these people into a "holding" room in the mind, and then finding that they are never brought up again is frustrating. It often happens, as did to me in this last reading, that I actually lost track of the antagonist in the crowd, and had to go back a couple pages to sort everybody out.
Another good lesson learned.
The Lost Children: A Charity Anthology