I can't tell you much about them except the following:
1. I have a 14Kt solid gold Wittnauer that I bought here (Philippines) a couple years ago. It is not signed "Revue" externally (dial) or inside the caseback (it only mentions Wittnauer there), however the movement is a Revue calibre 76/3 and is double signed ("Revue" & "Wittnauer Inc Watch Co.") and has the American import code of "AXA" on the balance cock.
2. According to one Wittnauer history article I came across (in Wikipedia), "The first Wittnauer's watch line were crafted starting from 1880, but Wittnauer brand was formally established in 1885, when Mr. Robert gave the title to Albert Wittnauer under the name The "A. Wittnauer Company". Wittnauer movements were at the beginning generally made for them by Swiss firms (Revue Thommen and others), while in later years Wittnauer used a number of different sources for their movements."
Of course, the Revue Thommen firm is better known for the "Vulcain" Cricket, though they were sold under the "Revue Thommen" badging in later days (for example, my 1997 Cricket is badged Revue Thommen & has no "Vulcain" signature on it).
Found some more with both Wittnauer & Revue Thommen info @http://lsyf.com/1954-longines-wittnauer-revue-thommen/