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.
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."
Audio problem: When young Selena is given the microphone by her dad, we hear her singing, but her mouth isn't moving.
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.