One thing about being a seat-of-the pants writer instead of a plotter is that you have to go back and make sure that the end matches the beginning and middle.
When I started Neeta Lyffe, Zombie Exterminator, I didn't know a lot about my characters. They really told me their lives as we progressed in the plot. LaCresha's little brother flirted with the idea of joining a gang. Roscoe has a condo in Malibu. Neeta's front door sticks.
There are world events I didn't know about either. Woody Harrelson is running for President. Iran has decided it's their turn to take over Afghanistan. Wow--where did this stuff come from?
From the fertile imagination of my twisted mind, of course, but I had to follow the twists to discover them. If I plotted, I would never have discovered them.
However, now I need to go back over the manuscript and make sure I laid enough clues and hints that events flow seemlessly. Just because I got blindsided does not mean my readers should be, after all.
How will I do this? I'll read it over once, taking notes, maybe even as I do my usual backward read for typos. Then I can insert stuff into the text as needed. Then, I'll read it aloud to the kids to see how well it flows. They are good at stopping me when I miss an important fact or hit them with something out of the blue. Finally, if I have any doubts, I'll ask my crit groups to keep an eye out for certain things.