I just got transported on a non-magical trip back in time at my local Buffalo Wild Wings, where they have a Mustang with very old code. Here's all the stuff I noticed that was not present:
* Super skill shot for 2 gears
* Mystery Ford awards for finishing modes
* Any distinction between just playing and finishing a mode
* Upgrade Scoring
* Burnout Multiball
* Roving top lane mode for free, easy points
Of course, it had lots less polish, fewer animations, more bugs, etc. that what I'm used to with the new code.
I still had a bit of fun, but the current code is night and day compared to what I just experienced.
I remember playing Mustang when it first came out, and my biggest complaint at the time was how blinding the flashers were. I guess there was enough to discover that I didn't realize how little there was in the programming at the time.