You can break minecarts/boats in spectator mode.

Steps to Reproduce:

1. Set your gamemode to creative. (/gamemode c)
2. Place minecarts and boats.
3. Set your gamemode to spectator. (/gamemode spectator)
4. Hit them until they break.

Observed Results: 

You can break them in spectator mode.

Expected Results:

You shouldn’t be able to break them.

Notes:

Not only normal minecarts and boats are affected. You can also break minecarts with chests, tnt, hopper minecarts and boats with chests.