Hits appear in red boxes instead of green

[acm14850]

When managing a game, hits appear as green boxes on the playing field, and outs as red boxes, except occasionally a hit (generally, but not always a home run) will show up in a red box.

[Sonny]

I've seem that several times. I think it means there would have been an out except for exceptional circumstances. In this instance the fielder would have caught it but because of the size o fthe field it was a home run. At least that is the way I interpret these things.