There was a glitch in the stairway level wherein, by getting hit by a ghost hidden behind a door when you are on your last life, you can no longer be damaged by ghosts that don't come out of doors.
In the Japanese version, it's possible to earn enough money to enter the ZUUL Building early by buying and selling the Ghost Alarm over and over again as its purchase price is lower than its resale value. This glitch is fixed in the International Release.
At the ending screen, "congratulation" is misspelled "conglaturation", and "proved" is misspelled "prooved".
Due to various programming bugs, such as the game trying to read the ending text from the wrong CHR-ROM page, the Japanese version of the game doesn't show the ending screen and credits at the end of the game. Instead, it only shows a black screen, followed by the text "ã‚Šã‚Š" (riri) scrolling onto it.