According to Fukio Mitsuji, the characters of Bub and Bob were made to get more female gamers into the arcade, which was very rare to see before then.
Contributed by gamemaster1991
Attachment
In arcade game's code are a number of slot machine icons, possibly intended for use in a bonus round that was never made.
Contributed by Antwan
Taito, the creators of Bubble Bobble, announced in 1996 that they had actually lost the source code for the arcade version of Bubble Bobble. All of the various ports were reverse engineered from the arcade ROM and earlier computer and console conversions.
Contributed by ThisGuyInTheSuit