According to The Cutting Room Floor, a website devoted to archiving unused content in video games, Tank is the first video game known to have unused content. Specifically, the game's score numbers are stored as one sprite even for double digit numbers, with the numbers going up to 63, despite such a score being impossible in the game due to the game's maximum 120 second timer and invulnerability frames.

Most geographic areas had two arcade video game distributors in the 1970s. Atari founder Nolan Bushnell tried to sign exclusive deals with as many of these distributors as possible, and then got his neighbor, Joe Keenan, to run a second studio known as Kee Games (named after Keenan, who led the company), which would sign an exclusive deal with the other distributor in the area, selling clones of Atari games with minor alterations. Bushnell would then move Atari workers into Kee Games - to avoid signaling that Kee has ties to Atari, Nolan Bushnell would release a fake press release condemning Kee for supposedly stealing staff. Eventually, Kee would release its first unique game, Tank!, which proved to be more popular than any of Atari's original games at the time, leading Kee to be officially merged into Atari in 1974 as Atari no longer needed exclusivity deals. Kee Games would be closed by Warner Telecommunications in 1978.