This set included an "Info Card" to provide new rules and rulings for players who didn't have the FAQ or the Players' Guide. The Info Card is not playable. It appears as an Uncommon card, and that annoyed a lot of people, which is why Daedalus offered to trade them for rare cards.
The distribution of the rare cards is unusual in Flashpoint. Daedalus decided to put a rare card in about one out of 4.5 packs (4 - 7 rares in each box), rather than one in every pack. Rare cards take the place of a Common card in those packs.
When you do the math, you can figure out that there were a lot more Rare cards printed than were distributed in boosters. Some were given away at conventions. Others were offered in a mail-in program where people could swap Info Cards 2-for-1 for random rares. The rest are gone, rumored to have been stolen from the Daedalus offices and sold on the secondary market (which means that some card dealer somewhere has a huge box of Flashpoint rares and doesn't know what they are or what to do with them.
Daedalus also introduced the "play as printed" concept in this set, with the new Alchemist Lair and White Ninja. Players were allowed to use the version of their choice (or to mix and match, if they liked) but the "maximum 5 in a deck" rule still applied.Thank-you to Stephan Vincent for providing some information for this page.