Saperstein's body moves within the coffin. In all the side views of the coffin, Saperstein's head and shoulders are clearly propped up so as to appear above the top edge of the coffin. When Santos looks down at him, it is clear that the head and shoulders are well below the top edge of the coffin.
After Saperstein dies, his widow holds a viewing or wake for her late husband. Jews don't hold viewings/wakes, and no family or friends are supposed to see the deceased's body. Also, Jews aren't buried in regular clothes. After the body is ritually washed, it's clothed in special white garments for burial. Finally, Jewish men are buried with both a head covering and their prayer shawl (tallis or tallit).
When Marcus is with Mrs. Sapperstein in the mortuary, his medallion (badge) doesn't have a mourning band.