Well, frankly, I could live better with the twin hypothesis than with the theory, that the guy, who shot himself on the roof also faked his death.
By the way, if there's anything to our guesswork, Moriarty's sentence 'I'm sooo changeable' would get a whole new meaning, lol!

I thought about that, too, Davina. But, as you say, it's not likely. True ambidexters are VERY rare, and an ambidexterous Moriarty would not turn the teacup, because he would be fine to hold the handle with either hand. Also, I cannot imagine, that the writer would create an ambidexterous Moriarty, just to confound us.
The whole thing could still be a big continuity error, but I get increasingly uncomfortable to chalk up every headscratcher to this. And again, there IS a Moriarty brother in the canon.

davina, we all saw but didn't observe, lol! No, I don't think, this one is a continuity error. This left/right hand thing is much too big for this. It's standard mystery novel stuff. But I like the way, they fooled us with the writing! If I weren't a leftie myself with lots of mirror image writing practice, I would never have caught on!

davina, when I wrote about the time lapse, I wasn't thinking of the time between the cabbie scene and the rooftop scene. I meant the time between Sherlock seeing the clean shaven Moriarty as cabbie and seeing the moustached Moriarty as Rich Brook, the actor at the SAME evening in Kitty's flat. Check out the time line: Sherlock sees Moriarty as cabbie, the assassin gets shot, Sherlock checks his flat for hidden devices and finds the camera. Mrs. Hudson complains about being in her nighty. At the same time Lestrade comes in and tells him about some doubts. Lestrade goes away. The burnt Ginger Bread man is delivered, while Mrs. Hudson is still in her nighty. She opens the police with the arrest warrant in same nighty. Sherlock and John get arrested, go on the run, see the newspapers, go to Kitty's flat, where they encounter moustached Rich Brook.  All this takes place in the dark and in the same evening/night. So we either have to conclude, that Rich Brook, the actor and Moriarty, the cabbie are not the same person or we have artistic license and a continuity error here.

Sherlock, I agree, I believe into the simplest explanation as well, though the stubble IS confounding! We're looking at a time laps of a couple of hours at most between Moriarty as cabbie and Moriarty as Rich Brook. Even the most hirsute men can't grow a moustache as fast as this. Trouble is, in a tv show you just never know, how much they bend reality!

I think, we all made too easily the assumption, that Kitty is a bad reporter and would not have checked Brook's credentials. For one thing, we really don't know, how bad Kitty really is. Actor Rich Brook is presented as a public persona, even if he is not well known. His resumme is easy to check, even for a bad journo. The counter argument always was, that Moriarty altered all the records, but he himself said, that this is bullshit and this kind of powerful code doesn't exist. Well, we can't have it both ways. If the code does exist after all, Moriarty was lying to Sherlock. If it doesn't exist, we have to conclude that the Rich Brook persona is real to a certain degree. I tend to assume the latter. If actor Rich Brook never existed, people would have found out in a very short time. And more important, John would know it. He was there, when Sherlock came face to face with Brook, and heard all the accusations. He would be VERY interested after Sherlock's suicide to find out, if there's any truth in the Brook story. Well, he must still believe, at least it COULD be true, mustn't he? We talked about John having found inconsistencies in Sherlock telling him, he's a fraud. I've pointed out some inconsistencies in another thread (and, as always in the times of the world wide web, others have beat me to it, as I found out), but Rich Brook never having existed would be a glaring biggie for John. So if Sherlock wanted John to believe in the 'I am a fraud' story for a prolonged period of time, he must have known, that the Rich Brook story would check out.
So, what are the conclusions:
The simplest one would be, that Moriarty had created 'Actor Rich Brook' quite some time ago as a fall back identity, which would be always handy and practical for a supervillain. A variant of this theory is, that actor Rich Brook IS Moriarty (Moriarty being his artistic alias, since it sounds more menacing than his real name). The actor, who was not contend being a small fish and decided to bec

He Sherlock, interesting, that you should post this! I started to feel mega uneasy about the whole Rich Brook situation. First I could not put my finger on it, but when I started to do some research on possible clues, which might really be continuity errors, I stumbled on this: When Sherlock takes a look at the cabbie, who turns out to be Moriarty, Jim is absolutely clean shaven, as Moriarty always is. Yet only a bit later, when he meets Rich Brook, he has a little goatie and a three day beard, which would take days to grow and  hours to fake with make up. I mean, come on,you can put on a false beard, but that's not, what we are looking at here. This could be absolutely nothing more than a big continuity error. But it doesn't inspire confidence, that in canon Moriarty has a brother with the same first name (Doyle wasn't THAT good with continuity either, lol, but MoGiss have used that more than once  to their advantage)  and, if you look up Andrew's acting resumme, you find, that he once played twin brothers (Dying City). One of them died in the war, but the other one came back to unsettle the wife of his brother. (Of course, Andy's acting career has nothing to do with Sherlock, but on the other hand, writers don't create stories out of thin air. They are inspired by something.). Commenters at other websites pointed out, that, when Sherlock said, that you can wrap up a big lie in a whole lot of truth, he's not talking about his life story, but about Rich Brook really existing as an actor,but of course not having been hired by him. As you point out correctly, the talk about the computer code enabling to erase and create records at will is bullshit, or at least Moriarty says so. I'm not sure, if there's any more than an error to it, but this would be a BIG slip on the side of the makers.
Of course these thoughts don't square with the fact, that the name 'Rich Brook 'is supposed to allude to 'Reichenbach', though Sherlock says himself at one point, that you never can co

Irene, Sherlock, or Ben for that matter, speaking elvish - now that brilliant thought has never crossed my mind. We should contact his agent. Tolkien wrote many elvish poems. How about the song of Beren and LuthienTinuviel? Though the elvish telephone book might be fine, too. My elvish is not THAT good. Mumblings would go undetected.

Irene, that's absolutely beautiful! Thank you, just right for my lunch break.
Yeah, let's have a whole thread dedicated to beautiful voices!
They dub everything in Germany. Normally they do a great job, but once in a while it's a pity.

Actually, we might just have stumbled on the clue, everybody missed. Spock really dies, but his body is conserved in deep space, and he is revived by 'Project Genesis', a secret scientific project for creating life on barren planets, which might have been developed by Dr. Stapleton in the Baskerville facilities, one of the project, she wasn't allowed to talk about. So Sherlock really jumps and dies, Molly conserves his body for three years, and Mycroft, who of course knows about the project, tells Dr. Stapleton to test Project Genesis for the first time on a human. Case closed. No clones, doppelgangers, dubious poisons or rubber balls involved. Who knew, it was that simple!