[Chmee]

From the list of known bugs you probably already know about this one Scot, but as I didn't see a mention of the particular quest, it's "Circle the Wagons... Er, Boats" at Fizzle and Pozzik's Speedbarge in Thousand Needles (what used to be Shimmering Flats). I had no exit button, and ended up disabling nUI6 to get out of the boat.

Edit: I did discover that, for this boat at least, if you find a place you can run it aground, you'll be automatically ejected, so no need to disable nUI6 to get off the boat.