If you try to fish in a boat while in creative the boat breaks/disappears.
Only in creative mode
Environment
Minecraft Version: 13w36b
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Confirmed.