In Somewhere In Time, where did the watch come from?
If the Martians could successfully negotiate our atmosphere enough to know that they could jet down here then they would know the proportions of our atmosphere. If they knew how our atmosphere worked then they tested. If they tested the air how did they not know it would kill them?
Dude, that would be some good drugs.
In the Spirit of Chronos, would might also ask:
Wesley Crusher?
Jar-Jar Binks?
Robin?
Hogwarts, obviously. It was glamoured to look like a watch, but we all know what it really was. It’s a funny story actually except for the tragic death part and the inexplicable lack of Seymour boobage.
Superman’s costume: where did it come from, and does he throw it in the washing machine after every saving-the-world?
Whatever happened to the son of Reed Richards and Sue Storm? And, of course, did any of the guests at their wedding think, “boy, I wonder what THAT honeymoon is gonna be like?” 
What was actually the deal with the island on “Lost”?
No, I mean, really.
Why does Empowered’s molecule-thin skintight powersuit, which must be in contact with her skin at all points to work, hence no undies, display camel toe?
Really, it will NEVER be answered in story. That has been made clear!
From Planet of the Apes:
How did Taylor walk around a planet where apes spoke, read and wrote 20th century English and not realize he was back on Earth?
From Conquest of the Planet of the Apes:
How did chimps evolve to be the same size as humans within 20 years of Zira and Cornelius landing when only one of them was their child?
From Battle for the Planet of the Apes:
How did all apes (chimps, gorillas and orangutans anyway) all learn to not only speak but fragment into social classes and castes just twenty years after Caesar was the only one who could speak a complete sentence?
LONG since answered in story. Pre-Crisis it was from Krypton and as invulnerable as he (not to mention as stretchy as Ralph Dibney). He washed it by flying through the nearest yellow sun. Actually he could have used his heat vision but flying through a sun was good for intimidating alien invasion fleets.
“Helm officer, move us into Earth orbit. Weapons officer, prepare for orbital bombardment. Science officer, have you located the Kryptonian? I wish him to see his adopted planet fall before us.”
“Yes, Captain. But --”
“What?”
“Well – he is – um – FLYING THROUGH THE STAR.”
“Seriously?”
“Yes, sir. One of the other ships scanned him dragging a third behind him INTO the star.”
“Oh. Um – well – maybe we should retreat.”
“Maybe?”
“Okay, definitely. Communications officer, signal that we are leaving. First Officer, take the conn. I have to change my pants. No special reason.”
Post-crisis, the answer is “his mommy made it for him”. Because he’s got some sort of protective telekinetic layer now, tight clothes are indestructible while he’s wearing them.
Don’t blame me. it was all Byrne’s fault.
Really! Flying it through the sun? OK, whatever - I should think it would be easier just to wash it, though.
As I recall from reading comic books as a child, it was made from the blankets and, er, swaddling clothes he arrived with from Krypton.
the lady or the tiger?
“Why don’t you just shoot him?”
Who is so vain that he probably thinks that song is about him?
David Geffen.
G-d, I love pissing off Skald.
What does it mean, “lay traps for troubadours who never reach Bombay?”
How does superman shave if he’s indestructible?
And don’t tell me he doesn’t, 'cause when he went bad in the Superman 3 movie he was all grubby and dirty and clearly went without shaving for a while.
Where the frak did Starbuck’s shiny new Viper come from?
What the frak was Starbuck?
It took 4 seasons to get to “God did it”? Really?
What happened to the rest of the cylons?
What really happened at the end of BSG? No, no…the events depicted in the gods damned finale didn’t happen that way. No sane band of space-warriors and their civilian charges would walk off into the wilds of an unexplored planet with only the clothes on their backs. Did the cylons and the humans kill each other in a glorious final battle? Cuz I could handle that.
I should have put your answer in a spoiler box. I’d look like a genius.
Anyway, to make you feel better, I am tessering you a couple of Thrace-model hookerbots.