During the scene while on board the aircraft when Roger's horse becomes agitated and the vet must give the horse a tranquilizer. The needle on the syringe is present when he fills the syringe, then disappears as he turns to administer the shot then re-appears after the shot is given.
The Pie in this film has totally different coloration than in the previous film.
When the horses are being loaded onto and unloaded off the aircraft, the engine covers are clearly displayed. These are only used when an aircraft is parked overnight, or stored out of service. They would certainly be removed long before flight (the crew are shown going through pre-start checks), and not placed back over the engines immediately after landing (they were visible as the "passengers" were getting off the aircraft).