Man O'Mars was John Hunter an Earthman raised on Mars to fight against evil Martians.

This was a one shot, but apparently Fiction House had hopes it would succeed as there is a house ad promoting it as one of "The Big Six of the comics!" alongside Jumbo Comics, Jungle Comics, Jet Aces, Ghost Comics & Long Bow Indian Boy.

Man O' Mars Man O' Mars #1
Of course we know now that there is no Martian civilization.
Then again it's such an obvious nit that it hardly needs to be pointed out.

The present day is 2036, but all clothes on Earth look like they come from the 1940s.
Well, they say fashion is cyclical... ;-)

Why is Martian leader Gurtil using Earth time references? 20th century, 1952. Doesn't Mars have its own calendar?

Page 3, Panel 2. Two ringed planets can be seen in the Martian sky. Way too big to be the closest ringed planets to Mars (and astronomers only knew Saturn had rings back then.)

The first Martian attack on Earth happened in 2021.
Something to look forward to... ;-)

In 2022 Tarkan, (one of the good Martians) lands on Earth & convinces the World Council that in time the bad Martians will attack again with superior weapons & the only way to stop them is to send 100 Earth boys to Mars to be trained in the ways of Martian combat & weapons to stop them & the council agrees.
Wait, what?

Life On Other Worlds
A science fictional travelogue of Uranus & Saturn.
While it might be possible for life to exist on those planets, it's unlikely to be anything like the large creatures seen here.

Page 4, Panel 1. Says the speed of light is 175,000 miles per second.
That's about 11,000 miles too slow.

Star Pirate
Apparently the main character's name actually is Star Pirate.