In an action sequence The Flash is running around an empty industrial chimney and sees Wonder Woman reaching out to grab her sword and gives it a little nudge to push it back to her.
However, further on he stumbles (which to remind all, is very, very fast, so much the Flash is effectively a blur) and Batman helps him out.
Is this a careless execution of a scene by the director to increase the amusement of the film or do comic fans really have fan-theories about this?