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 ?
According to the common version of the myth, Theseus left her in Naxos. He probably sailed more than one day from Naxos to Athens, with stops on his way. So this is not his final leg which is shown in the picture. In those time sailing at night was unusual. They tried to spend nights on the shore, which was possible in most cases because of the abundance of islands.
The picture has some other major inconsistencies with the myth. The boat was evidently painted by the artist as he saw it: it is a contemporary boat (18-20 century) since it has fore-and-aft rig, probably the gaff rig with a jib. All these are recent inventions. The Greeks used only square rig.
Also the boat sails to the right in the picture, which is opposite to the direction of the open sea, so it seems to be returning from a trip rather than departing. (Unless the land that we see at the horizon is another island).
I suppose the painter painted the landscape as he saw it, the boat included, and then simply added the Ariadne's figure, without much thinking.