I’m removing the You Had One Job tag. If you look at the boxes, they’re labeled with “Wild Rainbow.”
 
This is not an error, it’s intended. Their mane colors are different from their tail colors, and they have a tattoo-like mark going down their rear legs, and Sweetie Belle’s mane and tail even match the colors on her “tattoo.” They have a mixed color motif, and the boxes are clearly labeled “Wild Rainbow.”
 
Not a mistake.
 
Upon viewing the image in full again, there might be a possible mistake. While Sweetie Belle’s mane/tail colors match her tattoo, the other two don’t. Scootaloo is blue and pink, while Apple Bloom is purple and pink. If they swapped their mane colors, it would match their respective tattoos. This may or may not be an error, because rainbow implies multiple colors. So I won’t reapply the tag unless someone’s got more information than I have.

@hooon  
Maybe they’re trying to start their punk band again.

@wolfnanaki  
No! they get wrong hair color!

Don’t know what the “You Had One Job” tag is for. These toys were made well before they got their cutie marks.