The thing is, the camera zooms in on the torture droid's syringe, not giving you a look at what else it's got. I've seen the prop in person, and it's got various other nasty looking medical apparatus jutting out of it. It's also composed of two Artoo domes, so who knows what other nasties can pop out.The floating interrogation droid/beach ball from ep IV always bugged me. I think it all boils down to the syringe it's holding. I'm sure there's some EU something-or-other that goes more in detail on it, but just from what's on screen, it's ridiculous that a floating sphere would be more efficient to inject a person with something than, say, a person would. Always seems so stupid and takes away from a scene that is presumably supposed to make one worried for Leia.
Thanks for the photo. It's just one of those things that takes me out of the movie briefly (like seeing Artoo awkwardly walking down the stairs toward the Millennium Falcon in ANH) and it sure does not ruin my enjoyment of the movie. But yeah, maybe if the syringe wasn't on that droid, I would be able to focus on what other horrible things it could do.