Audio problem: When Chris drives up in the truck while Selena is mowing the lawn, Selena asks what he got. While you hear "junk food" his mouth says something else.
Continuity mistake: When Selena is singing "Como La Flor" in Mexico after the crowd was pushing into the stage, her mouth doesn't match the words to the song. Her mouth is a few words ahead of the song.
Continuity mistake: When Selena is in Mexico and is singing, she puts her microphone out into the crowd but somehow her voice didn't get any softer, so you automatically know she is lip syncing.
Audio problem: In the scene where Selena opens her boutique, she introduces Yolanda Saldivar. The camera zooms in on Yolanda, but you can still see that Selena's mouth doesn't move when she says, "She's my fan club president."
Visible crew/equipment: When Abraham is introducing the roles of what the children are going to play, he demonstrates what Suzette is going to do on the drums and falls back. If you see under him, you see a kind of pillow to break his fall. When the shot changes you see that it's not there.
Audio problem: When young Selena is given the microphone by her dad, we hear her singing, but her mouth isn't moving.
Continuity mistake: When Selena is lying on the bed and talking to her mom about how cute Chris is, the amount of her hair hanging off the bed changes between shots.
Continuity mistake: When Selena, her brother and father are in the van discussing touring in Mexico, in one shot Abie has his seat belt on, in the next shot it is off, the next is on, etc.
Factual error: When they are being kicked out of a Corpus Christi dance club in 1961 for singing do-wop, someone screams "We want to hear Tejano.". Tejano music was born in 1972 in Alice, Texas. In 1961, the correct term was "Tex-Mex" which later became "Chicano" which is now known today as "Tejano". The word "Tejano" was not known in 1961.
Continuity mistake: When the two Mexican guys are driving down the road to Selena, in the first shot where you can see their faces, the guy who has his hair combed back is on the passenger's side. Yet, when they stop for Selena, the guy with his hair combed is the one driving.
Continuity mistake: After Selena draws the cowhide trouser outfit the scene is where they're performing in them. In one shot her belt is secured to her waist and in others it is hanging.
Continuity mistake: While Selena is recording "I Could Fall In Love," her hands repeatedly switch from being on her headphones and off her headphones between shots.
Continuity mistake: When Selena's father and mother are arguing over the kid's first performance, Selena's mom's hair first is in front of her shoulders, than behind, and it continues like that for the duration of that scene.
Continuity mistake: In the scene where Selena and Chris are eating french fries in Chris's car, Selena's hair slips on and off her shoulder between shots.
Factual error: The opening scene claims to take place in the Houston Astrodome, but the inside shots show that the arena has a hexagonal shape to it. The Astrodome is a circle-shape no matter what is taking place inside, and it seats about 5 times as many people as depicted in the opening shot, despite the claim that Selena's show is sold out.
Factual error: In the scene where Selena is mowing the lawn, she is wearing Fila muscle ball sneakers. Those did not come out until 1996.
Continuity mistake: When the bus gets stuck, the sun changes sides throughout the scene. First, it's on the passenger side of the bus, then in front of the bus when the two guys in the car stop to help, then on the driver's side of the bus during the rescue attempt from the guys.
Answer: Looking at the credits on IMDB it does show that Panchito Gomez played young Abraham in Selena as well as the role in Tuff Turf. Given that 12 years had passed between the two movies, it's possible that Panchito had gotten older and didn't look like he was when he was 22 compared to mid 30s.