Can you play 'After You' when Callous Guards is in play?
The consensus on this "Official Guillotine FAQ" thread is that yes, you can play After You... with Callous Guards in play.  


  After you does not change the order of the line, nor does it "add" or
  "discard".  Ergo, you're fine to play it.


It's a consensus that no one has stepped forward to challenge for a couple of years, at the very least!