"Too closely" means as long as you don't figure out that the cowboys have 21st century mindsets in a 19th century setting. Confronted by aliens, they very quickly accept them as such and get down to the business of fighting back - very much what modern people would do.
Nineteenth century people would have seen aliens as devils or supernatural beings, maybe even as the result of witchcraft. Instead of rounding up criminals and Apaches to help them fight, I wonder if real 19th century people might not have held prayer meetings, hung some poor demented woman, or fled.
In spite of this quibble, C&A is a pleasant afternoon's entertainment. It is fun to see Hollywood turn out a well-crafted Western. The Western film is a true American art form and not at all common in recent years.
If you enjoy this mix of the Western and science fiction genres, see the TV series Firefly and the spin-off film Serenity. Both are available on DVD.
