Either way, the 'U' certificate it was awarded at the time is ridiculous in hindsight. Should be a 12 these days.
I wouldn't say so. For one thing certification has always been wildly inconsistent and very subjective from one film to the next. I've seen things in 'PG's that are worse then some '15's and '12's that are more tame than some 'U's I've seen. Have you ever read the kind of guidelines the censors supposedly go by? The more they try to quantify and specifically define where "the line" is drawn the more ridiculous and futile the whole thing seems. It's like the Zeno's Paradox of blood splatter and nipple exposure.
For another, it's just a pair of smoking skeletons. You see more shocking imagery in cheap carnival haunted house rides and as Halloween decorations. Really speaking, the severed arm in the cantina is way more explicit since, you know it's a bleeding, severed appendage of a (presumably) still living person.