The title is based upon the expression "Once in a while".
Samantha is here wearing the same exact costume she wore in 3 titles ago, in That Was No Chick, That Was My Wife (1967): under the same brown coat, she is wearing the same sleeveless white dress with the gold necklace with elephants motif and the same wide-brim white hat. They go to the same restaurant they dined in in that title.