Yes that was COAHTR. I believe that there used to be something in the Production Code for movies that said a woman could not be shown wearing a bra and half slip, it had to be a full slip. Of course on Elizabeth Taylor that works a little differently.
The last time I wore a full slip was at my 2 little's wedding - she made the bridesmaids' dresses and us buying slips was hella easier than lining the things.