you can ride any tipe of minecart in gamemode 3 (chest, furnace, with mobs)
What I expected to happen was...:
I couldn't ride minecarts filled with something

What actually happened was...:
I could ride both the minecart or the move, even if it was in the mine cart

Steps to Reproduce:
1. Go in gamemode 3
2. right-click a minecart that has something in it
3. You will be able to ride it