Mega Man X4 was released on both the Sony PlayStation and the Sega Saturn. While North America and Japan received both versions, Europe only got the PlayStation version. Capcom had initially intended to make the game a Sega Saturn exclusive, but later changed their minds.

The executives at Sony’s American PlayStation branch initially did not want to approve Mega Man X4 for the PlayStation due to a policy against 2D games.

The development team behind Mega Man X3 did not want to produce another sequel on the Super Nintendo and waited until Capcom approved the project for next-generation hardware.

Capcom took the initiative to make Zero significantly different in playstyle from Mega Man X. They based Zero’s attacks on traditional samurai techniques and gave him moves inspired by Capcom’s other series, Street Fighter. This was the first Mega Man game in which Zero had his own full campaign and separate cutscenes.

Despite its positive reviews, Mega Man X4 was considered a financial flop by Capcom, who then heavily scaled back the funding for its sequel, Mega Man X5.

X’s voice actress, Ruth Marie Jarman, was not told she was voicing lines for Mega Man X4, and believed she was voicing the original Mega Man for Mega Man 8, which she also worked on at the same time.

This was the first Mega Man X game to feature voice acting and anime-style cutscenes. The original English version was notoriously poorly dubbed.

Iris is the love interest of Zero in Mega Man X4, and strangely, this is the only game she appears in. The American version also scales down their dialogue, diluting the romantic tone of their relationship. Capcom reportedly wanted to make her a counterpart to Roll (from the original Mega Man series) for the X sub-franchise.

The Repliforce antagonists in this game were heavily inspired by the anime series Gundam.

Mega Man X4 reused sound effects from other Capcom titles, most notably Street Fighter Alpha.

In the Japanese version of Mega Man X4, there are subtle hints—later confirmed—that the hero Zero was in fact the final creation of Dr. Wily.