In this test,
2
1 720 5
12:00

is correct answer 5?

No. Correct answer is 1445. I do not see any explanation for this in the English version of the conditions, but in Russian version there is phrase "because of weather, economic and geopolitical reasons, THIS MOMENT, all aircraft will depart from the airport i to Di minutes later calendar". Ie in your answer Son-of-Sam use flight from previous day, but it flight was not late. Flights became late after 00:00. And Son-of-Sam must wait 24 hours and only after it he can leave from airport #1.