i had the same issue... i called the office (they're really friendly and the person who always answers the phones has a cool accent) and they told me the tour should be the last thing and go until around 2:30-ish. i have a 10/9 interview there and my flight leaves NO at 4:30... the admissions person told me i can always scoot out of the tour a few minutes early, that it was common, and there should be no problem making a 4:30 flight out of town.
hope this helps. feel free to call their office and ask about your specific question- they were very helpful. 🙂