The bread Lucy makes was real and was custom made by a Los Angeles bakery. After filming it was distributed to the cast, crew, and audience to eat.
On December 14, 2018, CBS aired a colorized version of this episode along with "The I Love Lucy Christmas Show" (S.6,E.11).
The bet the foursome made states that no technology made after 1900 can be used for a week. In wondering if electric light bulbs were in use at that time Lucy turns to Fred who annoyingly tells her to ask Ethel. In reality Bill Frawley was the only one of the foursome to actual be around in 1900 having been born in 1887 making him 13 years old at the turn of the century. Vance, Ball, and Arnaz were born well after 1900 in 1909, 1911, and 1917 respectively.
Lucy and Ethel claim that they'll lose the bet if they go to a modern beauty parlor; however, it's never explained how they acquired what looks like professionally coiffed fancy period hairstyles in the next scene.
The bread was from the Waldorf Pastry Shop on Larchmont Blvd. Los Angeles, CA. Julius Salgo, owner and baker, was on the other side of the set pushing the bread. Additionally, according to Shirley Salgo, Julius's wife, the bread was ordered to be multi-colored inside. This was to give the cast something more to laugh about.