What other movies wouldn't work today?

https://www.cnn.com/2023/12/24/travel/spirit-airlines-6-year-old-wrong-flight/index.html

But also once you're past security, which as I recall in the film where Kevin gets lost, he could definitely get on the wrong plane. Any sort of on flight check could easily be excused away with a new flight attendant or Kevin being covered by a cost or any other silly reason.