The roms we have right now are leaked prototypes from the mid-2000s. They were originally posted on AtariAge, but they were quickly deleted by AA themselves out of legal fear (the flashback was still new at this point). All of the games were there, but most were super early, unplayable builds. I specifically remember Food Fight only played the sounds and had a counter in the middle of the screen. All of those seem to be lost to time now, no one ever backed them up...
There's also the Missile Command port which wasn't included on the flashback, only some random 10-in-1 pnp from a few years ago. Not sure why they waited over a decade to release it - its definitely one of the better ports. I'm guessing because its based on the arcade original and not the 2600 port?