“Somehow overlooked” means that the lawyer and/or paralegal responsible for “Shepardizing” the case screwed up! IANAL, but my wife is one and used to do this for attorneys and they would review it before finalizing court filings.
“Shepard’s Citations provide a way to search updated case law and this is referred to as Shepardizing.”
“Every primary authority must be Shepardized, and this includes those cases such as Supreme Court rulings and courts in the same jurisdiction as your case to be considered. And every case, statute and constitutional provision must be Shepardized so the opposing side or judge does not call your side on it. All the facts are necessary for a solid argument in any case.”