Don't use it! It's wrong - for several reasons. 'Overlook' is a verb, not a noun. And even if it were a noun, it would obviously have to be preceded by 'an' rather than 'a'. You could use 'overlook' as verb, as John suggests. Otherwise, if you want to use a noun, you need to say 'oversight'. For example: "Why wasn't my name included in the list of participants?" "I'm sorry. It must have been an oversight." Just curious...where did you find this sentence? Whoever wrote it is obviously not a native speaker and is not to be relied upon as a source of correct English.

"Those details might be overlooked. Please don't let anyone else forget about them [the details]."

If you are talking about "overlook" in the sense of to fail to notice something or fail to do something, here are some examples" 1. Q: "Why didn't he respond to my email?" A: "Maybe he overlooked it." 2. I got so busy that I overlooked some of my duties.