Was this just for the film or did TCA fly often with two captains?
Around that time the introduction of the DC-8 had resulted in a layoff and I suspect the F/O, (and maybe also the S/O), may have had to go backwards for a while. At AC if you had been a Captain but had to go back to F/O status you kept your four stripes.
I flew with both of them as their F/O on the DC-9. Great gents to work with.
In the clip prior to engine start you can see two rear view mirrors up on the main dashboard (one as to wonder why)
The mirrors were to be able to see the Standby Compass which was located behind and above the pilots, almost a sort of periscope principal. Used on full ramp check when all headings were checked and then stowed. If the standby was ever needed in anger you would have had a bad day :-).