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.
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.
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.