In the title song, Frankie Laine mispronounces "dogies" as "doggies". A dogie is a motherless calf, not a canine.
In some episodes Gil Favor is seen wearing Wrangler jeans - rivets and the trademark "W" on two pockets. The Wrangler brand wasn't sold until 1947.
Most of the women actors on the series have hairdos that required hairspray (not available until the 1940s) and which were not "period correct".
Despite Gil Favor and his men being on several cattle drives, the majority are clean-shaven, which would be difficult and dangerous without access to clean water. It was also rare at the time for men to be clean-shaven when working around livestock.