This is more of a light comedy than a science fiction thriller. It's actually a film about the different stereotypes of nationalities, beginning with the "ugly American" and the "waggish British" reporters.
The film always moves briskly, due more to clever writing, good casting, and strategic directing, than on effects and big money. This is a textbook film on how to make a film look like it's more action packed than it really is.
We know it's a spoof on the nationalities from the start, as the pair of reporters are oblivious to their train car being dislodged, by accident, and rolling into a "duchy" that resembles the European duchy we get in classics like THE INSPECTOR GENERAL, THE MOUSE THAT ROARED, and others.
The duchy citizens also play to part.
However, like most good films, this takes stereotypes and changes them into three dimensional characters, or at least two dimensional. The film makes sure it doesn't lose its light hearted approach. It has the cult look of a Rocky Horror in that regard, of taking stereotypes and making more out of them.
This is a fun film, and well done, obviously low budget. There are no dull moments, which is more than I can say for most big budget science fiction movies. Much of this is because the film creates a very good atmosphere.
Never underestimate "atmosphere" and "fundamentals". This film has both.