Deliberate mistake: When Brian and Bilkins are at the demolition derby, Roman wins and gets out of his car. As he scans the crowd, he sees Brian. When we see Brian the logo on his shirt has a 3D effect to it that goes back and to the left. In all other shots of that logo, the effect goes back and to the right. This shot is reversed.
Deliberate mistake: The relay drag race takes much longer to complete than it should. Each leg is a quarter mile going and back, the cars involved should be able to make their runs in much less time than is shown. Brian even tells Roman that the Yenko (the blue Camaro) can do a quarter mile in 5 seconds flat, but it still takes ten times that long to complete the entire run.
Answer: The blue car with the white stripes is a 1969 Chevy Camero with a yanko engine. The orange one is a Dodge Hemi Challenger.