Wow This sounds really interesting.
I am not a pro so cant be too sure about whether these are worth while or not so maybe discuss with those in the know.
1:I heard of one brain teaser where after departure the aircraft has climbed through thousands of feet of cloud which also happens to be icing conditions, Then an electrical failure causes failure of pitot static heating including standby......Now a cabin pressurisation fault or smoke in cabin is forcing them down but as I understand it they are in danger as they descend through icing conditions in a rush with no accurate air data indications, so do they descend?... I heard it was a favourite on profiency checks but might be only relevant on certain aircraft types.
2:Another might be have both pilots operating under slightly different SOP's, Maybe one of them just joined from another airline. Subtle things like exterior light off at gear up for one and off at flap zero for another guy. Just generally have they guys expecting certain things at certain times which the different SOP's you have them operating under dont correspond..it migh set doubt in there minds...build it up and right through the flight to a critical item been missed. One Guy calls for after take off checks.. the other turns to him and states we dont have one ( which is a new idea for airbus moving towards quiet cockpit) or have a much abbreviated one compared to what he was expecting.
I think alot of confusion can be placed if you give them both slighlty altered SOP's or Ck-lists, which hopefully will prove they will question each other if something major is missed but none the less start the miss communications flowing.
3:Rush them a little with time critical scenarios, departure of funchal madeira in the direction where the runway end drops off into the sea. Immediately after takeoff severe fire in engine or cabin, eng shut down drills / smoke drills and Get down quick but what about the overweight landing procedure ( no fuel dump on a 320/737) onto a runway that is not forgiving with an overrun.
These are all sketchy ideas thrown together.