The antonyms for the phrase "alighted upon" could be "missed," "passed over," "ignored," or "overlooked." To "alight" means to land or settle upon something, so the use of the phrase implies that attention was drawn to that particular thing. However, using these antonyms suggests that there was a lack of attention or focus on that thing, and it was not recognized or acknowledged. This can happen in a variety of contexts, such as in a job search where a potential employer may overlook a qualified candidate, or in a social setting where someone may miss an opportunity for a meaningful interaction.