If you drop an anvil on a minecart, it breaks (or wobbles, depending on the height).
If you drop an anvil on a boat/armor stand, the anvil either breaks or passes right through.
They all should act in the same way. It's weird how wooden objects are immune to anvil drops when metal minecarts aren't.
-All types of minecarts
Anvils don't break:
All types of boats