This was something raised recently on the Ozformers fan forum, and I'd never thought about it myself... so grabbed the toys, a screwdriver and did this quick fix.
On the back of their dragon neck, there is a lever that you slide back to straighten out the neck. On the first version (Megatron - the red one), the slide lever wasn't meant to lock in the "straightened" position, but can be. The later blue version (Cryotek) had a little tab of plastic added to the neck section for that lever to lock into... however, the lever was left facing "backwards", preventing it from locking into the tab.
The quick fix is removing the screw on the lever, turning the lever around, and replacing the screw.
This is one of the easiest fixes, of what may be a production error. There are a few other production errors over the years that have been a little more complicated to fix, so I've never tried attempting it before in case it damaged or destroyed the toy.
I just thought I'd share this one, with pics to show what needs to be done.