The following features in the game are unlocked by entering the corresponding code.

Unlock Central Park Game:
Enter NYC as a code.

Unlock Free Play Mode in Ace High:
Enter UNO as a code.

Unlock Free Play Mode in Big Shot:
Enter UJP as a code.

Unlock Free Play Mode in Black Hole:
Enter LIS as a code.

Unlock Free Play Mode in Love Meter:
Enter HOT as a code.

Unlock Free Play Mode in Playboy:
Enter HEF as a code.

Unlock Free Play Mode in Xoltan:
Enter BIG as a code.

Unlock Free Play Mode in Strikes 'N Spares:
Enter PBA as a code.

Unlock Free Play Mode in Tee'd Off:
Enter PGA as a code or alternately complete the table goal for Big Shot.

Unlock Free Play Mode in Goin' Nuts:
Enter PHF as a code or alternately complete the table goal for El Dorado.

Unlock Payout Mode:
Enter WGR as a code.

Unlock Custom Pinballs:
Enter CKF as a code.

Unlock Optional Tilt:
Enter BZZ as a code.

Type the following codes without the quotes at the 'Enter Code' screen to unlock the corresponding effect in the game.

Unlock Free Play in Strikes 'N Spares table:
Enter 'PBA'.

Unlock Free Play in Tee'd Off table:
Enter 'PGA'.

Unlock Free Play in Black Hole table:
Enter 'LIS'.

Unlock Free Play in Goin' Nuts table:
Enter 'PHF'.

Unlock Free Play in Playboy table:
Enter 'HEF'.

Unlock Free Play in Love Meter:
Enter 'HOT'.

Unlock Free Play in Xoltan:
Enter 'BIG'.

Complete the following tasks to unlock the corresponding new 'Free Play' modes.

Goin Nuts: Free Play Mode:
Complete the table goal for El Dorado.

Teed Off: Free Play Mode:
Complete the table goal for Big Shot.

To make the flippers disappear you need to get a score of 100,000 Points. The screen will flash and the flippers will disappear and reappear when you get 150,000 Points.