In Chapter 4 Stage 2, there is a room with a of Alastor and Another Joe in a yellow costume. In the first Viewtiful Joe game, before the fight with Another Joe, Joe makes a bet between the two that whoever loses most wear his costume in yellow.
Alastor reflects his lightning off of statues during his fight. The statues are of Gran Bruce, a boss from the first Viewtiful Joe.
The demo for Viewtiful Joe 2 on the PS2 Holiday 2004 Demo Disc contained a glitch that would erase the player's memory card.
In early trailers, a multiplayer mode was shown off. One player would play as Joe while the other player would play as Silvia. However, sometime during development, the mode was dropped.