When someone says "Summer Olympic venue", I think of "arena", a city called Atlanta wouldn't cross my mind. Also the train question is a bit too obsucre for my taste. Lastly, where did you lose "alpaca"?
OK, tweaked the Olympic clue. Sorry the train question was a bit tough; on the plus side, now you know Amtrak's most famous (and rapid) service for future quizzes! Alpaca was obvious enough to leave out.