This occurred in a desert Biome village at night.

Steps to reproduce:

1 get the rails to both me curved and trying to connect from a one block height difference.

2. Get a villager onto the lower block, with it surrounded by the other block with the rail and two block on the sides, not holding rails, and the 4th side having a rain connected to the curved one.

3. Position another villager (or other mob and even yourself) to touch the villager's collision box so that it's being pushed into the upper rail block at a diagonal angle as to ensure a mine cart would bounce that way.

4. Shift click to place the mine cart on the rail block with the villager instantly being placed in it, and push the mine cart.

Note: when i did it, a villager pushed the minecart and they were "talking" to each other.