Macromedia Hidden Game
1. Click Help > About Flash
2. Quickly, *double* click the Macromedia logo with the two upward pointing arrows, to the right of the About Box.
3. Click the "thanks" button to the right to make th logo bounce up and down.
4. Click the "team" button to the right to play the rather cool "Gary's Car Jump Game!"
5. Try to get past 12 cars, that's as far as I got! :)

Bouncing logo
Go to the About Box of flash, then point your mouse on the M logo. There's a small clickable spot there that makes the logo bounce (just like in the doubleclick egg).

Alien Containment Facility
If you look at the Flash 4 CD-ROM, there is a directory called "Third Party" where third party software resides. In that directory, there is another called The Alien Containment Facility.
Open up the index.htm or the Flash movie. Click the first enter button to get to the main screen. Click the Menu button to get to the main menu. Click the first button "What is a Flashpack?" On the robot interface (named Login Z) you'll see four screws, one in each corner. Right click on the screw in the upper right hand corner and choose zoom in.
Keep doing this until the screw is big enough to click on. When you click on it, you'll see it has a secret "Enter" button underneath. You'll probably have to zoom in as far as you can to see the movie. Once you've clicked on the enter button, right click anywhere in the Flash movie and choose "Show All" to get back far enough to see everything.