How many times have you seen this in a movie? A character walks into a house, and leaves the door open. The scene is long enough for you to see that the door isn’t going to close by itself. For some reason, that always ticks me off.
In a book or story, we sometimes do the same thing. A character gets out of bed in the morning, has breakfast, and leaves the house to go to work — in his pajamas. Or whatever he was sleeping in. Maybe he sleeps in the nude. We don’t need a detailed description of our character taking off his sleepwear and getting dressed, but not mentioning it all can leave a hole that’s going to sidetrack some readers. “Holy cow! Did he just walk out of the house in his altogether?”
I had this oversight pointed out to me by a beta reader. A character leaves the room to do something that is probably going to take a fair amount of time. The remaining characters are having a real-time discussion which can’t possibly take more than a couple of minutes. And the first character pops back in, not even out of breath from having performed his errand at blazing speed and raced back.
It’s amazingly easy to overlook these little glitches. A character gets up from where he’s been sitting. The only problem is that he was last described as pacing around the room. Another character gets in the shower, apparently without undressing.
We don’t always need to know how a character got from here to there, or how long it took, or what condition he was in. But if you’re trying to convey realistic action, it has to be — realistic. In the scene where the character came back long before he could have finished his task, I could have dealt with it in any one of several ways. I could have made the conversation longer, but only if that made sense for the scene. I could have had him come back and mention some reason why he was back so soon. Or I could have filled in some action during or after the conversation so that his return didn’t happen unrealistically fast.
Once you see these little lapses in continuity, it’s usually easy to fix them. The really hard part of writing is spotting them.