* A bit minor, but it's a little surprising that Superman isn't spending his birthday with his parents.
** Countered by FridgeBrilliance when you remember that Superman could easily spend part of the day with his parents and part of the day at the Fortress. It's not like he has a long commute.
** In regards to the comic version, if we're talking about the Kents, it was Pre-ComicBook/CrisisOnInfiniteEarths. Jonathan and Martha Kent died shortly before Clark went to college Pre-Crisis.
*** Pre-''Flashpoint'', a flashback in ''GreenLanternCorps'' (vol. 2) #24 showed a similar scenario of the story. Suggesting it was restored in Post-''Infinite Crisis'' continuity. So Superman ''could'' indeed spent part of his birthday with his parents before going to his Fortress. If so, that would leave the question of ''how'' Mongul escaped from his Black Mercy-induced fantasy (since he enjoyed it so much to think it's too good to be true), let alone escape from the black hole Superman dropped him in.
** And for the animated one, there's also the element of FridgeBrilliance that since the Black Mercy attacked Clark while he was in the Fortress, surrounded by memorabilia of his Kryptonian heritage, it's no wonder that he dreamt of life on Krypton.
* So, why didn't Mongul kill Superman after using the black mercy on him, it seems pretty careless of him to assume that nobody would show up and remove it.
** He probably did knew, but he just didn't care. I mean, he hardly came of as the most humble person ever, he probably just thought he would kick their asses and get a chance to talk about how clever he is.
** Another possibility would for Mongul to keep Superman in his suspended happy land while he conquers the Earth, than bring Superman out of his happy world into a burning wasteland as a trophy, caught in despair for the two worlds he has lost.
** Mongul explains it in ''Justice League Unlimited'': he wanted Superman to suffer from having the Black Mercy removed.
-->'''Superman''': Do you have any idea what you did to me?
-->'''Mongul''': I fashioned a prison you couldn't leave without sacrificing your heart's desire. It must have been like tearing off your own arm.
** If Superman doesn't get out of the fantasy, then Mongul has a handy little Superman trophy he can show off and gloat with towards everyone he's conquering. Besides, what's the point of imprisoning someone in an inescapable fantasy prison if you're just gonna kill them seconds later? Might as well enjoy it for a while.
** And perhaps Mongul attempting to kill Supes would cause the Black Mercy to falter. Why fight Superman when you can just take him out of the way? Besides, in the comic version, nothing could rip it off without Mongul's special gauntlets. Only the animated version had the IKnowYoureInThereSomewhereFight trope.