Can you play a 3D movie from a usb stick/external hard drive on a 3D TV?

If you get the right copy why not? Your TV is 3D obviously it can play 3D movies

Thanks. So I just have to figure what “type” of 3D movies it plays, and I’m ready to go?
(I don’t know a thing about TVs)

Yeah, usually just dvd rips of 3d movies will work.

Great, thank you!

Your TV might be equipped to play it directly from a USB port built into it, check for one of those. Then you’ll have to plow through the menus to find the media on the USB stick and select it.

If your TV doesn’t play movies directly from the USB stick you’ll have to play it on a computer that can output a signal (preferably HDMI) to the TV.

It is. It’s got 3 USB ports. I just wasn’t sure if the 3D Blue-ray player does some magic before it sends the signal to the TV, or can 3D movies be played from the USB directly.

Only your TV can tell you for sure. One thing you could do is just try it.
You may have to crack a manual to figure out how to get to the USB media.
And the manual should give a description of its capabilities to play various media.
3D is a fairly compute-intensive decoding job but heck that’s not a 3d TV for nothing, it’s possible.