There are 8 basic levels in the game. Each set of 8 has an increasing level of difficulty set in the game logic

1 - 8	Ducklings
9 - 16	Mother duck
17 - 24	Ducklings and mother duck
25 - 32	Double ducklings and mother duck
33 - 40	Fast double ducklings and mother duck

After this, level 41 is the same as level 33, and so on ad infinitum, except with the time gradually being reduced to 400 at level 65.

The game display showing the current level at AEC2 can only accommodate two digits, but the internal counter at 6EEB is an 8-bit unsigned number. Therefore, after level 99, the counter overflows to 0, but play can continue as it if were 100, wrapping round again to 200 and progressing to level 255 (displayed as "55"). After this, level 0 is on the full difficulty level, then the level counter finally overflows to 1 and difficulty drops to the easiest. Unlike Pac-Man, there is no other related bug so play can continue until the heat death of the universe....

The mother duck is in play on every level, but its updated location in the routine at A0C8 is ignored on levels below 9. The player will still lose a life if they walk into her.

The game's protagonist is assumed to be called "Henhouse Harry" after Chuckie Egg II. However, no name is stored anywhere in the original.

The tune at the start of the game is "The Birdie Song" which was a top five hit a few years before the game was released. It is one of the most annoying and infuriating tunes of all time, with the possible exception of Mr Blobby.

The tune played when the player loses a life is a brief extract of the traditional Spanish guitar piece "Romance Anonimo".

The game supports the Fuller Orator, a hardware extension to the Fuller Box audio box with a dedicated speech module. The routine for this is at 9CC2.