The Flash is not Flash Gordon
This confusion has been around since I was born. Let me explain in detail. Flash Gordon was devised as a comic by Alex Raymond in 1934 and ran until 1943. More often than not, people assume Flash Gordon is The Flash. They're all expecting Flash Gordon to be super-fast, but really he's nothing but an ordinary guy who's been forced into extraordinary circumstances. Steve "Flash" Gordon is themed an athletic Yale graduate who gets kidnapped and taken on a rocket ship to a distant planet Mongo where they discover that some meteorites that hit earth were actually weapons devised by Ming, the merciless ruler of Mongo. Oddly, Flash is friends with his kidnapper and one other guy and they go on adventures together on Mongo and later on other planets. That's all there is to Flash. He holds no super powers and you might call him an ambassador of Earth. The 2007 SciFi series twists it around and uses inter-dimensional travel since "Rocket Ships" were a new concept in the 1930s. So maybe 50 years from now dimensional portals will be common-place.
The Flash was a comic devised by Gardner Fox in 1940 and the story ran through 2006. The Flash is actually several people who all took on the title after acquiring super speed. Jay Garrick (the original 1940s Flash) was smoking in the lab, fell asleep and inhaled heavy water vapors; Barry Allen (in the mid-1950s) unrelated to Jay was working in a lab when lightning struck a case of chemicals that sprayed him; Wally West (in the late 1950s to 1980s) is the nephew of Barry and Iris West and had the same chemical accident, but was dubbed Kid Flash; Bart Allen (who appears in a new series started in 2006) is the grandson of Barry and aged faster than normal until he was taken back in time to be taught by Wally how to slow down his aging, and he took the name Impulse, then later Kid Flash.
Now the Flash has super speed and later can travel through time, so even though they are dead now, they reappear in places excused by time travel. For the most part they travel through dimensions to different earths and after a little fun they put on red spandex and a lightning bold and turn to a life of crime fighting. The whole time-travel and dimensional-travel part is made up later on so I prefer the original stuff.
In addition to all this, Gardner Fox also created the Hawkman superhero. He appeared in a comic with The Flash. This is a guy with a fake wing suit and anti-gravity metal and is considered the reincarnation of an Egyptian prince, Khufu. He came from another planet, Thanagar, and stayed on earth as a crime fighter.
So as you can see these two Flashes are not the same. They have different origins and different goals. Flash Gordon didn't get into a freak lab accident and instead he traveled to another planet entirely. The Flash(es) are all related to each other and either had a freak accident or were born freaks and have super powers. They traveled dimensions and through time but they didn't really take any epic space flights.
SciFi has basically took the two worlds and smushed them together. The adventures are those of Flash Gordon, and their form of transportation between planets is through a high-tech dimensional rift generator to the planet Mongo. Fans have been asking to see his super speed and SciFi promised to have it in the second season, but I hear it was canceled. I'm rather glad it was because I would rather it be a story of Flash Gordon with an updated form of travel, and not The Flash with the wrong story line.
I hope I've made myself clear. The Flash and Flash Gordon are two heroes that appeared around the same era and are now extremely easily confused with each other. Flash Gordon is far less known because it ended when The Flash was picking up steam. So please don't blend their stories. Steve Gordon is not the same person as Jay Garrick or Barry Allen. So you're going to have to change actors if you think you can put the two stories together. Just stop it and make a new story about four Flashes. Most people hate when a movie doesn't match the book, but imagine the outcry when the movie/tv show doesn't match the hero. Don't make this confusion any worse. It's been like this for many years, and someone needs to correct it.