Marcia Mae Jones received fan mail from disabled children all over the world after playing Klara in this movie.
For the scene in which Heidi is butted by a goat and falls over, Shirley Temple was butted for the first few takes. Although she later said that being butted was not painful, her mother Gertrude Temple became concerned for her safety and insisted that a stunt double be used.
Shirley Temple developed throat problems after she accidentally swallowed fake snow during a winter scene, and the crew had to shoot around her for two days.
The movie was filmed during the summer, and Jean Hersholt's heavy costume once caused him to collapse from heat exhaustion.
The scene in which Heidi is suddenly squirted in the face while milking a goat was planned without Shirley Temple's knowledge. A tube of milk was attached to the goat udder where Temple couldn't see it, and when she was squirted, her surprised reaction was genuine.