Earl is 43. Fran is 38. Robbie is 14. Charlene went from 12 (mentioned from season 1 and 2) to 15 (mentioned in season 4). Baby went from 1 to age 2, but because of his terrible attitude, the family convinced him he had turned 3. Mr. Richfield is 42.
Jim Henson originally got the idea of a live action show featuring animatronic Dinosaurs after being impressed by the technology his Creature Shop was developing for the first Teenage Mutant Ninja Turtles film. When the show went into production the same technology was then used to create the Dinosaurs, as Jim Henson envisioned. Many of the Ninja Turtle suit actors even worked as various Dinosaur suit actors for the series.
The Baby character on the show was often referred to as "the baby" during the first two seasons, but was sometimes called "Junior" by various members of the family in a vain attempt to give him an official name. Finally, in a 1992 episode, Baby Sinclair is taken to the Cave of the Elders where he is given his official name: Ooh Ooh Ah Ah I'm Dying You Idiot Sinclair. The name was later taken back in exchange for his new official name: Baby Sinclair.
Another reason for the dinosaur family name to be Sinclair is that when the Sinclair oil company was still in existence, its gas stations had as their logo the image of a green four-legged dinosaur (the brontosaurus or apatosaurus.)
The full-size dinosaur costumes came in two parts, a full body suit and a separate animatronic head. The head contained radio-controlled motors that moved the jaw, lips, eyes, and eyebrows. For closeup speaking and lip-sync, the heads were separated and operated by a team of puppeteers.
The initial design for Grandma Ethyl Phillips was a pterosaur. A winged creature, which are often erroneously called dinosaurs and generally referred to as pterodactyls. She was to be depicted as always hanging upside down, usually in a closet. But the design of the puppet would have proved to be incredibly difficult to manipulate. So she was changed to her final design seen in the series.
Earl is often seen sighing as he walks across a room. This was done to allow the person inside the costume the chance to see where he was going, as the mouth was the only area the could be seen out of when it was opened.
In many episodes, a rock band can be seen on the TV called "Lizzard Skizzard." While the name is an obvious reference to classic Southern rock band Lynyrd Skynyrd, the actual band has far more in common with the many "hair bands" of the late '80s/early '90s.