After finally watching Season 4, I agree with all the questions asked before - and with all the people who said that there are no answers and we should suspend our disbelief. Still, I have a few questions to add:
If I can believe House M.D., there is a medical condition where people seriously don't feel pain - it's not necessarily a sign of mental illness. So why did everybody automaticall assume Euros was crazy?
"You don't lock up a child because a dog goes missing." - well, no, but it wasn't a dog that went missing. Another child was hidden away and presumably drowned by Euros. So why was the little murderess alone in her room, playing with matches, instead of being under close observation/being interrogated - or already shipped off? (Btw, it's surprising Euros got out of her room where the fire started, meaning it should have started slowly enough, but they couldn't save the house. Well, depending on how well insured Musgrave Hall was, the Holmses might have been more than happy to be rid of the drafty, impossible to heat place...)
Why was Mycroft staring at the drone like hypnotized instead of doing something about the patience grenade BEFORE the movement detector activated?
Why does he ask about Speedy's when "the neighbours should be safe" and it's clearly Mrs. Hudson's flat that's on the ground floor of 221? And how can John and Sherlock land on Speedy's awning (and wouldn't that be rolled up when the café is closed?) when it's next door? Given how all three shake off being blown out of the house (awning to soften the fall or not) - does that mean it's now canon that they are some sort of supernatural beings, like vampires?
Back in HLV Mycroft said something like "No prison could hold Sherlock" and prefers to send him off on a suicide mission (is it suicide when you are forced to do it?) - when Sherrinford was there all along to "detain the undetainable". Maybe he didn't want to lock up Sherlock in "hell" - but then why do it to Euros?
Mycroft is magnificently menacing when he asks the Governor about Euros ("if she ever left the Island, I guarantee, you won't") - but then, when he gets the perfect chance and a compelling reason to make good on his threat, he caves in and shows himself to be the spineless a... I've always thought him to be... Wasn't he supposed to be better than that?
Why does John not know how to kill a person? From the moment he asked the Governor's name it was clear he wouldn't shoot him. Killing is best done without thinking about it, I speak from experience. (No need to call the police, my victims were poultry and sick rabbits - all of which were completely innocent and much more likeable than David.) That was my first thought. The second was: Is John truly the abusive monster we've seen in TLD and tortures the governor on purpose for all the trouble he's caused?
Last but not least I just can't make up my mind whether The Final Problem is the worst story ever written - or a really, really clever political commentary...