Deliberate mistake: In the scene where the Punks follow the Warriors into the bathroom, Rembrandt sprays the head punk with his red spray paint. However, the spray coming out of the can is clear, not red.
Deliberate mistake: During the space battle, one of Drax's men gets his back pack blasted. (1:46:37) His entire pack explodes so that his jet pack and life support are destroyed. But as a result of that blast, all the parts from his suit FALL DOWN! Even though there's no gravity.
Deliberate mistake: None of the helicopter's in the movie have the Army markings seen on Vietnam era Hueys. The most you'll see is some crooked, faint and inaccurate stencils in the wrong spots. (00:37:50 - 00:51:25)
Deliberate mistake: When Rocky meets the kid that has his entire overbody and head covered in gypsum you can see that it is fake as the gypsum on the kids head is loose. The kid can move his head inside of it. (00:12:35)
Deliberate mistake: When the inmates first leave their cells we see at least 2 that have white or light colored shirts on instead of prison blue.