Revealing mistake: When Pinballs is squeezed in between the landing-gear door and the fuselage/landing-gear, you can see in the face that it's a dummy. (00:53:35)
Suggested correction: That absolutely looks like Dave Chappelle and not a dummy.
Character mistake: When Cyrus and Johnny-23 are talking they both pronounce the Spanish version of Johnny-23's name as Juaniyo. That is not how Johnny is pronounced in Spanish. It is pronounced Juanito with a T. Normally I would have chalked it up as a language barrier but Danny Trejo is of Spanish ancestry. He should have known better. (00:20:41)
Suggested correction: "Juanillo" is another, though less common, diminutive of Juan.
I can appreciate you doing a google search but you would have noticed in your google search that the Juanillo you speak or is predominantly an Asian name and is not a translation of Johnny in Spanish. I am Spanish and can assure you that it was a mistake as Juanito is the correct pronunciation. Thank you for doing your due diligence however he was not playing the role if an Asian.
It should be pointed out that there's a town in Mexico called Juanillo and Juanillo Beach is in the Dominican Republic. So it is a word Hispanic and Latinos might be aware of.
Don't know why the previous guy said that Juanillo is not a common name in Spain... I am Spanish and know 2 guys that go by the name Juanillo. I would say that not only Juanillo and Juanito, but also Juanele are commonly used in Spain and probably Latin America as well.

Continuity mistake: When the Poe family is reunited, Trisha can be seen holding on to Casey in the close-up. When Casey hugs Cameron in the wide shot, Trisha is not holding her.
Suggested correction: She pulled away from her mom and went to her dad.
Stupidity: After Nick discovers the parole letter about Po, he crinkles it up and throws it down. After Po kills him, wouldn't you think the first thing he would do would be to pick up that letter and also take the letter that his daughter wrote and put them in his pocket so that no one else could discover them? (01:01:00)
Suggested correction: While I agree that this would have been a good idea, I've never thought of this in all the times I've watched this movie. Apparently, Cameron didn't either. The fact that it didn't cross his mind is a character decision, not a movie mistake.