tablet and big, soft, over the ear earphones. We've had the wired version of these leapfrog headphones for 3 kids over 10 years and they are the best
And yes, the car seat is a great call, although we always gate checked ours because all three of our kids at that age were very calm and comfortable cuddling with my wife. The car rental companies charge an insane amount of money to use their car seats.