As many people alive today as have ever lived? Wouldn't that mean no-one had ever died?

Come to think of it, what was Clara doing in the opening scene with all those post-it notes?

Didn't she acknowledge that she was being old-fashioned in her choice of words?

When are you referring to? "Father's Day" was a "no, you can't rewrite the timeline to bring back a loved one" episode. Not that Dr Who has ever been too consistent with its rules.

St Paul's is a popular tourist attraction and is also used for religious purposes. Why has no-one noticed that it's full of skellingtons?

It's almost impossible to give a clue to a twist in a long-running plot without the internet as a whole figuring it out. (These days, the twists that surprise us are mostly the same ones that annoy us because they make no sense.)
The good thing is, even if it's not a surprise to the viewers, it can still be a surprise…

I didn't notice it at all. Is that what that logo was?

Where did all the metal to make them into cybermen come from? Answer: same place the new moon came from.

Obviously, they'd make it too obvious to make you think it wouldn't be anything so obvious, in order to catch you out by making it be the obvious one after all. So predictable they'd go for a double-bluff. Saw it coming a mile away. Which is why it caught me completely by surprise.

2. ???
3. Profit!

I found it difficult to tell who was in which suit.

"there's no real reason why Kuvira's rule couldn't be stopped militarily by the rest of the world."
At the cost of a catastrophic world war. Assuming the other nations could even muster an army powerful enough to beat Kuvira's extremely large and well-organised force - I'd have thought they were all fairly peaceful and…

Zaheer crippling the avatar during his murder attempt didn't exactly help the situation either.

You mean you haven't murdered Mr House and taken his place?

Bloody Irish, stealing our coal-mining jobs…

But the alternative he chose was so stupid. It's like if Batman sees the Joker killing hundreds of people, and said, "Well, he always escapes if I catch him, and I don't want to kill him, so I'm going to let him go. Also, no-one else is allowed to hurt him."

If you write out all the air dates on a grid, they form a cipher explaining the true purpose of aglets.

Unless you're Stan.

Yeah, the movies make billions of dollars. The comics? They exist, from a business viewpoint, largely for the purpose of testing out ideas. Hey, this guy wants to team up that talking raccoon with an animate tree. Sounds stupid, but it's only a comic. Let's give it a shot!

Well, it was to contrast with the Civil War era of heroes beating each other up and the Dark Reign era of villains trying to do the heroes' jobs. So it ought to have been the sort of thing that the people complaining here would like.