I can't really blame people for thinking Rita is the fastest as AT do emphasis the speed, you would expect it to be the fastest.
What annoys me is when people at "the" in front of a rides name, I feel a desire to punch them in the face, correct them of the error and the personally drag them out of the park by their hair (I refrain of course and sometimes go with the simple "there's no the in the name"). Can't say it annoys me when people drop the "the" though as I have been guilty of doing that with the swarm.
It also really annoys me when people say "Thorpe park had nemesis first, alton towers just stole it".
When people stand outside a ride saying it's too scary them when at the other side of the park, they say they want to go on it.
And the other thing is when people say "nemesis is like 20, it's time they should get a better ride in its place" and then I reply with "no, no they shouldn't, it's 20 and still the best coaster in AT".