This has to be the most pure and wholesome interpretation of the Wrong Place/Wrong Time genre.
While you guys nailed the genre scenario itself, what we're missing here is the story surrounding the event which should be an inciting incident.
For example, what happens after the girl gets splashed? Are there any consequences? What if she was holding her friend's phone and it got wet and broke? This genre is often less about the thing that happens to the person in the wrong place at the wrong time and more about how that character deals with the situation they are now in.
TITLE REVIEW: Watercress is a very peaceful title, and for the most part this is a very peaceful film. Perhaps you could have spent more of the film's duration setting up the peaceful nature of the film only to end on a dramatic tonal shift as the girl gets splashed by the buggy?