Today I visited a tar pit and got about 19 liters of tar in a barrel.
Later I built a rowboat.
I picked up the barrel of tar and right clicked the rowboat.
After that I could not find the barrel. I was no longer carrying it; I couldn't see it on the ground, and picking up and moving the rowboat didn't make it visible.
It was night, and I've had trouble seeing things at night before.
But lighting a fire (not right beside this, but nearby) didn't help.
And later (within 20 minutes?) I got weird display behaviour, increasing lag, and was eventually disconnected, as if the server had crashed or some such.
I have no idea if the two are related.
So I'm posting now, rather than waiting for dawn in Haven.