Robert Dalban
For fans of tiny unimportant details, the second professor whom Daniel Gélin visits in order to get funding for his expedition is re-dubbed by Robert Dalban (at least it sounds almost exactly like him), the great character actor of these years. He is also the actor who dubbed Clark Gable for the French version of Gone With The Wind.
It's one of those fun little moments you have when watching movies of this period, and recognizing all those great character actors.