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.
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.
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: 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.
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.