The texture of the slime is green even though the slime is blue. In some versions it's vise versa either way they don't match. The particles also have the issue. 

Originally I think it was blue. Then they changed it to green, now blue again. This bug has occurred since builds in TU (console edition) but, never use to be there. they use to match the colors. One version I found even had a blue slime ball not the green one.