A little history about the 'G' rating for this movie.
This film was in a group of 18 films that were the first to receive a rating from the MPAA in 1968. The original ratings were G, M. R and X. The films are listed below. I looked thought the user comments for each film to see if anyone mentioned the rating.
the 7 "G" rated films:
"Angel in My Pocket" - comedy
"Chitty Chitty Bang Bang" - musical comedy
"Dracula Has Risen from the Grave" - romance/horror
"Great Catherine" - British comedy
"Head" - musical comedy starring the Monkees, comment about the rating, should have been rated M
"The Impossible Years" - comedy, comments about rating, should have been rated M
"The Shoes of the Fisherman" - drama
the 6 "M" rated films;
"The Brotherhood" - crime drama, re-rated to PG-13 in 2001
"Diamonds for Breakfast" - comedy
"The Fixer" - drama
"Hellfighters" - action
"Killers Three" - crime drama
"The Night They Raided Minsky's" - comedy
the 3 "R" films:
"Joanna" - musical
"Lady in Cement" - crime drama, re-rated to PG in 1972
"The Touchables" - drama
the 2 "X" rated films:
"The Killing of Sister George" - black comedy, re-rated to R in 1972
"The Miracle of Love" - German documentary
The MPAA came up with the ratings because of the concern over increasing amounts of bad language, violence and sex in movies and Hollywood did not want government regulation. The M rating was changed to GP and then to PG. The PG-13 rating came about in 1984 and the NC-17 in 1990. The MPAA copyrighted the ratings except for the X. So you can see that rating of films has had its problems from the start and it seems the rating system will always be a source of controversy.