Boats with mobs going inside minecarts

So, I was making a iron farm and I needed to get a Villager inside a place. I decided to use minecarts for him to get there, I brought him with a boat, placed a minecaft, and suddenly the BOAT got INSIDE the MINECART WITH THE VILLAGER INSIDE and started going at full speed, and flied to the ground. The Villager died. I'm confused af, not sure if this is intended or not.

The screenshots show the part where the villager flied away/The iron farm