While Starla is doing the morning announcements, the clock in the hallway reads "4:22"
The close-ups on the football field during the game show the game being played on Astro Turf. The aerials show real grass.
The Texas "No Pass No Play" rule is enforced only at the end of each 6 week period, not at the moment the grade falls below passing. Starla would have been allowed the remainder of the 6 week period to get her grades up before being suspended from the cheerleading squad.
The teacher puts the audiotape of Genevieve's "confession" (actually with the poisonous words of Starla) into the CD driver instead of the tape section; the closeup even focuses on this when he tries to turn the record off.
The opening narration has Starla mentioning famous people that were from Texas, but three of those mentioned are not native Texans: John Wayne was born in Iowa; George Bush was born in Massachusetts; George W. Bush was born in Connecticut.
When Starla gets out of jail and is entering the lobby area, we hear someone answer the phone "Splendona Police Department". It is actually the Splendona Sheriff's Department.