I just got the game today, and my copy has 20 Residential Area cards, so after setting up the four initial player hands there are still 4 of these cards left over. The instructions don't say anything about extras; are these just in there by mistake? (I don't seem to be missing any of the other cards, fortunately.)
Each player also starts with 1 Apartment card. Flip 4 Residential Area cards over to their Apartment sides and deal 1 to each player for his/her starting deck.
Under Preparation, the following cards form each player's starting deck:
4 x Residential Area
1 x Apartment
1 x Convenience Store
1 x Hospital
1 x Factory
1 x Central Park
IMPORTANT: If you play with fewer than four players, you do not put the extra Residential Area cards in the General Supply. Put them back in the box.