When you're as popular as Valiant is you print a lot of books (especially in the early 90s!), and when you print a lot of books a few production errors sneak out. A few even look pretty cool.
Turok: Dinosaur Hunter #1 had a print run of almost 2 million (one of the largest in history) so you'd imagine a few errors would sneak by. Check out this copy with the red foil misprinted on the Valiant logo and title logo:
The weird lines on the chromium card are not an error, they appear on the scan only.
For comparison, here is the printed version.