I just noticed something extremely weird about this painting. Usually the people in Rockwell's paintings look like they're caught in the midst of action, ordinary, everyday action. In this painting, though, every U.S. marshall is in exactly the same pose, as though they had been marching in formation in a fairly unnatural way, sort of like shuck and jive robots. The little girl's arm and hand placement mirrors that of the marshalls. The lack of heads reinforces the bizarreness.
The tomato is a bit weird, also, for its placement in time. If it had been thrown only milliseconds before, the juice wouldn't have had time to run down as far as it did. So, the tomato throwing was to have occurred before the group reached that spot.