What do you get when you combine bad acting and historically illiterate writer ? You get the Lost Legion. I would say that the title of the movie gave you the real impression of the movie itself.... i.e.: lost.
Bad script can be the cause of bad movie, but so is bad acting. This is one of the movie where you have both of them. I am not a history buff, but know enough about the Roman history or at least know where to find the reading material about it. Just in case the director or the writer of the Lost Legion is reading this article, you can find some simple information on the website called Wikipedia.
If you can not or do not want to follow the history line, just name the country on your movie some "abracadabra country", that way you don't insult the intelligence of the people watching your movie and nobody can complaint that the director or the script writer are quite illiterate in history.
Forget about the Roman army, there is no such army on this movie, not even a CGI army. The setting was barely enough to justify as a screen setting and the green-screen action were done so badly that you can actually see that the background is coming from some other movie.
My suggestion is that if you do have the money to spend, give it to the homeless guy on the street. And if you have the time to spend, sitting in your backyard doing nothing is still better than watching this crap.