One of the most unshakeable truths of planning WDW vacations is that the plan is invalid as soon as your airplane touches down. Having said that, if your airplane really lands at 1:30, and you have a rental car, you'll be at the Poly by 3:00 and will have more than enough time to get to the MK by 5:00. If you're taking ME, or some other schedule-dependent transportation, you may not have enough time.