250 pieces in one bag? I don't think so. The most I've ever seen in one bag is 50 and they were all envelopes. Plus, how do you misload in a trailer with smart scanners?
Had someone fit over 140 small yellow envelopes into a bag before.
As for misloading with scanners ...my only guess is maybe two people were loading the trailer, one scan, one build the wall, bag set aside as a misload and the other didn't notice, grabs it, tosses it up?
In my center, loaders are supposed to immediately walk missorts out of the trailer and place them inbetween doors but with everything falling off of the rollers they rarely get to move unless an extra body is assigned to clean up the floor for them, so missorts just get set on the floor inside the truck usually.
Edit: Our trailers are a mess because our only extendos are used for unloading, all the outbounds are rollers, and when the flow is heavy, im sure you don't need me to tell you how much of a mess rollers are compared to extendos.