I'm sure they must have given some explanation as to why three guys who were each declared legally dead for several years suddenly reappeared, but I can't remember what those explanations were. Does anybody know or was it just ignored?

Hal would be the easiest as he lived a lot of his life drifting from job to job and place to place. He could just say he was off backpacking in Asia for a few years, but Barry was a somewhat prominent member of the Central City Police Department and Oliver Queen was a prominent billionaire businessman.