Continuity mistake: When the movie ends, Mr. And Mrs. Darling, Wendy and Nana are by the window looking at the sky. In the aerial angle they all disappear.
Continuity mistake: When Mr. Darling is getting dressed, a jar of water suddenly appears no the night table behind him.
Answer: They never officially confirmed; but it was likely castor oil or morphine. Both were used around this time period as a common "medicine" for children.
Cocaine, heroin, and alcohol-based elixirs were also commonplace at that time and considered "safe and effective" for children.
raywest ★