In the earlier seasons of the show Belita Moreno, who plays George's mother, can be clearly seen wearing some heavy "age" makeup. This may be due to the fact that she is only ten years his senior. Later the makeup shows up less, most likely after the audiences accepted Belita as his mother.
In Season 2 Episode 13, "Super Bowl", after Benny's brother Joe dies, it is said that Benny is the only one left (having been preceded in death by her mother, father and then her brother). However, in Season 6 Episode 4, "George Testi-Lies for Benny", George contacts Benny's mother to testify at her trial.
In Season 2 Episode 14, "The Valentine's Day Massacre", as well as in many other episodes it is mentioned that George and Angie went to (and dated) at the same school in California. However, when Angie's dad Vic moves to California it is insinuated that Angie was raised in Florida, as she was born in Miami.
Constance Marie's character (Angie Lopez) couldn't possibly have gone to the same high school with her husband (George Lopez) unless her family had moved from Miami to L.A. and then moved back; this is a story problem never fully addressed throughout the series.