Everything feels under control. You arrive at the airport early, your boarding pass is ready, your suitcase is packed, and you’re confident nothing can go wrong. But modern travel has changed. Increasingly, it’s not the huge mistakes that cause problems. It’s the tiny details travelers overlook because they seem too insignificant to matter.

Airports across the U.S., Mexico, and Latin America have become more precise about security and travel requirements. A liquid container can look perfectly reasonable and still fail because of the volume printed on its label. A carry-on can pass one inspection and suddenly be rejected at the gate because of its wheels, handles, or extra few inches. And sometimes, the problem isn’t your luggage at all. One small detail on your documents can bring the entire journey to a stop.