A good friend of mine . . . who shall remain nameless . . . . just got out of a "come to *****" meeting because a major change to an important fixture in their product was missed. Not a good day to be him . . .
It's scary to admit, but missing a poorly documented change can happen to anyone (to a varying degree of severity). It all comes down to your processes, and how tightly you're managing changes to your product with ECO/ECRs.
Obviously, working at Arena has convinced me that you should just set things up in an electronic change management system and call it a day, but a lot of people still use excel, email, notebooks, file cabinets, and a variety of other methods to manage changes to the product, and depending on where you are in your process, that could be perfectly fine.
No matter how you manage change in terms of system, I think there are some common issues that you have to deal with at one point or another.