Expert mode:
Highlight a difficulty level and press B + Select.

Slot machine mode:
Press Start to display the mode screen. Hold Select and press A to change the mode to "Slot". A slot machine will appear after a two player game is completed and change the number of tokens available.

Flip opponent's chips:
Press Select, A, B(2), A, B, A(2), B, Up, Down, Select(2), Start.

Replay:
After completing a game, allow the NES to idle until the title screen disappears. When demonstration mode begins, it will include all the moves played in the last game.