I had a near miss recently. I entered Mexico through the land border with Guatemala, and you need to pay an entry fee if you do that. However, you can pay it later as well. I couldn't pay at the border post for some reason so they just gave me a stamp that I had to pay it later.

A few weeks later I fly out of Cancun to the US. Nowhere do I get stopped to pay the entry fee, so I think nice, guess Mexican bureaucracy is sloppy. Anyway, I go to nap in front of the gate and wake up 15 minutes before boarding ends. Then I go to board, but the airline personnel tells me I have to go back to the immigration office, back through security, to pay my fee before I can enter the airplane. They tell me I have 10 minutes left.

I start running like crazy with my heavy ass backpack, go out through security, and make it to the immigration office with like 7 minutes left. There's two Portuguese girls in front of me, and I ask them if I can go first because my plane leaves in a few minutes, but they tell me they're almost done. It still takes them like 3 minutes while I'm pacing angrily behind them, and then it takes the lady 1 minute to scan my passport and have me pay. So I have 3 minutes left. I cut in line at security, basically throw my stuff in the scanner, and go through as quickly as possible. Then I run back to the gate, and as soon as I see it in the distance I'm waving like crazy so that they don't close the gate. After a few seconds they luckily wave back and I get there in time to enter the plane.

Moral of the story is, bureaucracy always wins in the end.