This game has hidden developer credits.
In Wrecking Crew, Mario begins his new career as a construction worker, only to find the job description didn't mention evading monsters.
Present at the beginning of the ROM, at offset 10 (similar text can also be found in Stack-Up):
Programed by T.NAKAMURA TOMOYO chan Y.SOBAJIMA AKINA chan 1985/4/25
Virtual Console Changes
In Japan, the Famicom version allowed players to save their level designs to an audio cassette tape through an accessory called the Famicom Data Recorder. This accessory was never released outside of Japan, so non-Japanese players couldn't save their level designs, despite the manual promising that development was underway on a method of doing so. The Virtual Console version allows players of any region to save their level data internally, without the need for an accessory.