While the head-swapping stuff perhaps isn't one of the more "realistic" Star Wars scenes, that whole sequence still comes across to me as a more stylized continuation of the usual R2/3PO dynamic. In terms of forced humor, though, that's actually how I read some of the Anakin/Obi-Wan banter at the beginning of ROTS. That little scene where Anakin defends R2 by telling Obi-Wan how the little droid is "trying" comes to mind, as it makes it sound like R2 is usually a useless tag along rather than the pretty darned dependable companion from the first two films. R2 engaged in a misadventure fits a bit more with the OT version of the character, so I suppose I can kind of see why they would work that in, but even then it seems to me it's a bit late in this particular trilogy to go that route--might as well have saved the misadventures for the OT as a flip side to the eminently dependable PT version of the character. Or at least not make it sound like the droid is always getting into mishaps when all his prior PT actions seem to be anything but. The ray shields thing and Obi-Wan's "we're smarter than this" sticks out as a bit forced as well. To me Obi-Wan just comes across as a little too loose in that whole opening.