In the painting Ariadne, by Arthur Streeton, seen here:
Ariadne is seen crying, with a ship with white sails in the distance. Presumably, this is depicting a heartbroken Ariadne watching Theseus sailing back to Athens. However, we know two things from the myth:
Theseus sailed back to Athens using black sails, which caused his father, thinking this his son was dead, to kill himself (as they had previously agreed that returning from Crete with black sails meant a dead Theseus).
Theseus sailed with black sails because he forgot to switch to the white ones, suggesting that he was originally sailing with black sails. (In other words, I am assuming that on all other trips related to the Minotaur myth, Theseus typically sailed with black sails.)
As such, either:
Streeton is indeed depicting the departure of Theseus, and merely painted the sails of the wrong colour.
Streeton is depicting a different event/myth/trip altogether, in which case, which one ?