Brakes on trains work opposite of how they are described. Air is used to release the brakes and when the air is lost, as depicted, the brakes would have been applied to stop the train.
Amy mentions to Lucas, before the train leaves Toronto, that he'll be excited to see the ocean along the way. Both Toronto and Chicago are hundreds of kilometers/miles from the closest ocean (namely the Atlantic). She should've instead mentioned he'd be seeing lakes instead (namely Lake Ontario, Lake Erie, and possibly Lake Michigan.)