Years ago, I was traveling LGW-STL-SNA (TWA, naturally) and I had two incidents on one journey. The first leg, LGW-STL still tickles me today: as the FA announced "Welcome aboard TWA flight XXX to Saint Louis", an entire family sitting near me got up, grabbed their bags and dashed for the door. The FA came back and asked what the problem was and they stated (we are traveling to 'Saint Louis (impose French accent here, something like "San Louie"), and must have boarded the wrong flight". After two or three seconds, everyone in the cabin started to giggle, understanding the miscommunication between British and American English. Still to this day, I think "San Louie" sounds quite a bit more exotic than "Saint Louis".

On the second leg, STL-SNA, a man seated near to me began to talk of how glad he was to be returning home to Orlando (I think, some Florida city) after several weeks in California. I then asked him why he was traveling via Orange County to get to Orlando, and he said "because Orlando is in Orange County" then giving me a rather odd look. I felt terrible to break it to him, that he was actually on the way back to California... and at first he did not believe me... but soon was set straight, thankfully enough.