Cave walk up and cave walk down warps are not completly disabled by the "Cancel Warp" warp type. Link will still play his cave entering animation when he steps on them, and then reappears either below the cave (if it was cave walk down) or above the cave (if it was cave walk up, potentially trapping him). Entering a cave that is canceled also stops the music for the screen, thought it restarts once Link leaves the screen.
http://rapidshare.com/files/75723595/BugTest2.qst.html
This is the test quest that demonstrates this bug. Two screens below the start has the canceled cave walk down, while the screen two down and one to the right from the upper left corner of the BS Overworld has the canceled cave walk up.
Windows build 679, Z3 Movement Disabled