For the record, it is possible to get a piece of paper jammed so far inside the duplexer rollers in the back of an Epson ET-3830 Multifunction Printer / Scanner that it is not only completely invisible from the inside, but that it cannot be removed without disassembling the duplexer:
It jammed while attempting to print another batch of Geek Scratch Paper with a semilog grid, without actually duplexing the sheets. The specs say the printer can handle 4×6 paper, so I assumed 4.24×5.5 paper would be Close Enough. Apparently not.
Print ’em two-up, chop the sheets down the middle, pad and glue, and it’s all good:
The Smell of Molten Projects in the Morning 
That’s one special design then. I remember seeing the adjective “multifunction” in some instrumentation over the years (likely HP or NI) and immediately twisting it around and calling it multiMALfunction. Mostly because I can’t help myself in having fun with words. Truth be told that the subject of this post was automatically converted by my brain as “Deluxe Paper Jam”, but indeed it seems like it was.
The episode began with jamming two little sheets, only one of which was visible. Removing that one cleared the jam, but all subsequent sheets jammed hard. Eventually I realized something else must be wrong, pulled the duplexer out of the back, spotted one tiny corner that hadn’t been completely crumpled inside, and utterly failed at removing it.
Couldn’t’a done better if it were designed that way!