Very good call, John. It looks like the animator had a Luger to examine and disassemble, but never got clued in on the actual firing sequence. The motion shown follows approximately what happens during HAND cycling -- the knurled knobs never strike the ears because the receiver is being pried (levered) back as the extended tail of the rear toggle link works against the back of the frame.
As you say, during firing the entire cannon recoils and the whole point of the design is that the toggle can't trip to unlock the breech until the knobs strike the ears (and the slug is on its way). It's easy to see how an inexperienced person could assume that the hand cocking sequence was the same as the firing sequence -- overlooking the rest of the story.
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