Those Irritating Plot Details

I am about three quarters of the way through the current WiP (Work in Progress). I have finally hit that all important point where a detail I threw out at the beginning as the plot equivalent of a gun going off must now be explained, which means I have to stop writing forward and sit down and think through the actual detail of the detail, if that makes sense.

I know. I know. A plotter of a different sort will have had all this worked out before they got going.

I am not that plotter. Except whe