According to multiple reports, battle encounters shouldn't be triggered when boarded. Only with the airship vehicle, other vehicles (boat and ship) are OK.
Also, it seems like airship vehicle shouldn't have sprite animation when not boarded.
For all vehicles: the sprite does some weird movement when moving it on map, it looks like some incorrect graphics update.
Test case kindly provided by MudarraP.
Also shows landing issues in mountains, not sure if a bug, as the forest is not landable and works. Not tested with RPG_RT.
Slow-mo of the movement issue