The answer is yes, but let's explore why.
The "Father of Pharmacy", Pedanios Discorides, circa the year 60 of the common era (CE), was the first to explore the effects of this plant in his writings on the discovery of herbs. The mandrake plant has had quite a long and enigmatic story, partly because it belongs to a species of plant whose effects in humans are highly narcotic, but still medicinal. The root of the plant contains alkaloids that can be used for anesthesia, and its fruit was once called the "love apple", as its consumption was thought to enhance the libido of the lucky recipient.
As with most plants of this category, a certain air of myth and notoriety comes with the territory. This has brought with it many stories and legends about its origins. Among its religious legends, the plant is said to have been molded with the same dirt that Adam was molded by God, and that the devil wanted the possess the plant.
Yet, the legend to which Waiting for Godot refers is one specific superstition that has been historically documented as a fact! Although it is not a fact, the legend is indicative of the rudimentary and illusory beliefs of the Middle Ages. It can be found in Thomas Newton's An Herball for the Bible (1587) where this man of vast knowledge writes of the plant with most assurance
It is supposed to be a creature having life, engendered under the earth of the seed of some dead person put to death for murder
This legend is what prompts Vladimir and Eragon's dialogue.
Estragon: What about hanging ourselves?
Vladimir: Hmm. It’d give us an erection.
Estragon: (highly excited) An erection!
Vladimir: With all that follows. Where it falls mandrakes grow. That’s why they shriek when you pull them up. Did you not know that?
Estragon: Let’s hang ourselves immediately!
Hence, "where it falls mandrakes grow" does refer to that kind of fluid.