Trivia: The voice of Mary Poppins' parrot head umbrella is David Tomlinson (Mr Banks).
Trivia: This was Julie Andrews' film debut. Her role won her an Academy Award for Best Actress.
Trivia: To celebrate the film's anniversary and release on DVD, there was a special screening of the film, at which Dick Van Dyke shared a humorous personal memory. On his way to the original premiere of the film, Dick Van Dyke's limousine ran out of gas not too far from the theater, so Dick himself got out and pushed the car to the red carpet.
Trivia: The medicine bottle that pours different colours was a real working prop. Karen Dotrice and Matthew Garber were not informed of its purpose, so Karen's shriek of delight is genuine.
Trivia: The film was shot entirely indoors.
Trivia: Matthew Garber was scared of heights, so they gave him 10 cents each time he went up in a harness for the tea party on the ceiling.
Trivia: When Mary Poppins is singing in front of the mirror during the "A Spoonful of Sugar" sequence, her reflection starts showing off, to which Mary replies "Cheeky." Julie Andrews ad-libbed that comment.
Trivia: As well as singing the lyrics for "A Spoonful of Sugar," Julie Andrews also provided the voice of the robin, whistling in harmony with herself.
Trivia: Mary Poppins and Mrs. Banks never speak to one another throughout the whole film.
Trivia: Child actor Karen Dotrice (who played Jane Banks) said in later years that she and Matthew Garber (who played Michael Banks) were shocked at Julie Andrews' frequent foul language and smoking on the set of "Mary Poppins"; and they were also aware of something very wrong with Dick Van Dyke (who was seriously hungover much of the time and having bouts of suicidal depression).
Chosen answer: For a good explanation, go to The Straight Dope: http://www.straightdope.com/mailbag/msupercali.html. It will give you pretty much everything that is known about this odd word.
Richard Welty