If you're used to seeing an actor playing a particular character, it can be hard to put that character out of your mind when you see the same actor in a different role.
It's recently come to my attention that this goes at least triple if the character you're used to seeing them play is a master of disguise. Suddenly it doesn't even seem incongruous that they're not dressed the same way as usual!
(Well, Rollin Hand is a master of disguise according to the script. What that usually seems to mean in practical terms is that a startling number of the people the IMF team finds a need to impersonate in the first place turn out to be played by Martin Landau. :-)