My Vernier Dynamics Cart jumps off the track when after colliding with the magnetic end stop.

The adjustable end stop was not designed for anything beyond gentle collisions when using the magnets. The track-jumping behavior is expected.

To use the end stop with higher-speed collisions, remove magnets from the end-stop, and use the plunger cart instead. This combination will keep the cart on the track for all but the most enthusiastic student.