The view of the world in this movie is clearly dated, but as the movie is from 1918, it's hard to put it against it. What is more impressive is everything it does right. This is not a movie using science fiction as a gimmick - it uses the genre to explore ideas about the time it was made. In the end of the first world war, here's a movie exploring if mankind can live in peace, how we treat our prisoners, how life in a submarine (here: spacecraft) can affect ones mental health, how pushing science forward is a global affair, and can unite different parts of the world, and so on.
While I am not sure just how much the general public knew about astronomy - this movie presents the mission to mars in a way that seems realistic. It takes time, people doubt it, and it takes a toll on the members. They point out where mars will be as they leave Earth, and where it will be when they arrive. The spacecraft itself is like a submarine with a propeller and wings. Mars itself I am sure was quite a mystery back then, so the fact that they made it Earth-like is very understandable. It also opened up for them using Mars and Martians in a way that let the film makers comment on the people of Earth.
The movie is not subtle in the message it is conveying: people on earth should stop with wars and violence and rather go with love. In the end of the most gruesome war in world history up till that point - that sounds like a good message.
The worst part about this movie is the one evil character in it. He serves little purpose, and undermines the underlying message of the film that humans are capable of being good.
