Two incidents stamped in memory...one quite recent, one a decade back.

1998: Days that I started flying a reasonable amount, and starting to get to know aviation/transportation terminologies, expressions, etc. Also, days of the paper ticket in booklet form, stapled at the bend (you know the kind). Flight is for 1700 hours, but the "1" in 1700 is printed ON the border for the time box on the ticket, so looks like "700". I know its an evening flight, and so presume its 7.00 pm. Had to wait 24 hours for the next flight. Luckily, departure was from my hometown...

2009 June: Indigo Airlines in India - flight code is 6E, printed in large, block letters on the boarding pass. I board, and am arguing vehemently with the passenger in seat 6E that he's in my seat. FA clears the air and directs me to 30D. Only good to come out of this was that 6E would have been a middle seat ! I've flown (HAD TO) on 6E twice after that, and had other passengers argue with me. At least, I don't laugh at them now...joke was on me earlier, wasn't it !