What do you mean with "They appear to travel several hundred meters when thrown which is weird."?
If you drop a grenade or stone out of a moving vehicle, it will fall down but it will still fly into the direction you were moving.
That means in theory without air resistance:
If you fly with 100 km/h in a height of 100 meters, the dropped grenade or stone will travel 125,42 meter until impact.
If you fly higher, for example 200m, it will travel 177,38 meter until impact.
With air resistance it wouldn't be so far but still over 100 (or 150) meter.
You were speaking of high speeds so the travel distances would be much higher.
That is not magic, these are physical laws.