Besides the inconsistencies with the white markings or lack of them on the Warner's hands, there are quite a few other inconsistencies with their markings. For example, in one panel on page 4 in the Animaniacs comic "Re-Animaniacs!", Yakko's chest is white. In the last panel on page 8 in the same comic, Yakko's tail is white, which may make people think the tip of his tail is actually white. This would then imply that Yakko actually painted the tip of his tail all this time.
In the Animaniacs episode "Space Probed," Wakko's chest and belly are shown to be white. Sometimes, Dot looks like she has a white belly because herunderwear was left white instead of the standard light pink.Also,the white on each of the three Warner's feet that is supposed to end at their ankles is sometimes shown to end at their knees or in between their knees and ankles. In Wakko's Wish, the Warner's father looks like he has a white chest, belly, and white on the ventral side of his neck.
The Warner's faces and feet are supposed to be white and I leave it that way. I personally like to draw Yakko with a white face, white on the feet up to the knees, palms of hands and thumbs, and belly; Wakko with a white face, feet, hands, chest, and belly; Dot with a white face, feet, hands, and belly; William with a white face, feet, ventral side of neck, chest, and belly; and Shelby with a slightly differently drawn white face, white feet, hands, belly, and tail tip.
Yakko, Wakko, and Dot Warner; copyright ~RonaldtheFox on deviantART