There is another possible explanation for the missing parts. A customer may have returned it to the retail store after losing (or pilfering) those parts, and the store could have rewrapped it with shrink-wrap and returned it to the shelf without ever checking the contents. Most stores have a shrink-wrap machine in the back room, and when used, you can't tell the difference from the original factory shrink wrap. I know, I used to work for one of those retailers (briefly) and was not happy to observe this practice.
So it's quite possible that Revell was not at fault.