Seriously, if you do not want to read spoilers about "The Final Problem", do not scroll down this post.
At the BFI last Thursday, some notable cast and crew from Sherlock talked about "The Final Problem" following a special screening of the episode.
Moriarty (Andrew Scott) is still 100% dead.
The gut-wrenching scene when Sherlock rung Molly was written at the last minute and replaced a scene that Moffat says the Sherlock crew hated.
It appears that Moffat doesn't see Sherlock and Watson becoming romantic in the future.
The creators really want more episodes of Sherlock, but whether they'll happen is down to the stars' availability.
"The Final Problem" episode is all about Sherlock realising that he is stronger than Eurus and Mycroft.
The episode is also Sherlock becoming more like the other famous Sherlocks adapted from Arthur Conan Doyle's books. "That is him becoming the Sherlock Holmes of Basil Rathbone and Jeremy Brett."
Redbeard not being a dog but rather a person was a plot twist dating back for quite a while.
Mycroft said this scene in "His Last Vow" was a specific reference to the Eurus/Redbeard storyline.
If "The Final Problem" is the final Sherlock episode, Gatiss sees the show being an entire backstory of how Sherlock and Watson became the men in the books.
Siân Brooke (Eurus) auditioned for three separate roles and only found out that all three roles were one person after being given the role of Eurus.
Moffat, in a passionate speech, says that the show's success is all down to Sue Vertue.