CAST
Johnny Weissmuller: Tarzan
Maureen O'Sullivan: Jane
Johnny Sheffield: Boy (as John Sheffield)
Reginald Owen: Professor Elliott
Barry Fitzgerald: O'Doul
Tom Conway: Medford
Philip Dorn: Vandermeer
Cordell Hickman: Tumbo
Johnny Eck: Bird
Martin Wilkins: M'Hona

Original Music by David Snell
Non-Original Music by William Axt ~ Sol Levy
Cinematography by Clyde De Vinna 

TRIVIA

• Filming ran for two months, beginning in June 1941 and came in at just under a million dollars. MGM boasted that the film had been in production for two years. It was released in December 1941.
• Filming Locations: Mostly filmed on the MGM lots, Lake Sherwood and Iverson Ranch in California ~ Silver Springs, Ocala, and Wakulla Springs, Florida.
• Due to many budget cutbacks following the death of Irving Thalberg many stock shots from former movies were used. The crocodile fight from Tarzan amd His Mate was used for the third time.
• Screenwriter Cyril Hume presented a screenplay that included a reworking of the rejected ending that had killed off Jane in Tarzan Finds A Son! He was replaced by Myles Connolly.
• The villainous Joconi tribe was named after production  manager Joe Cohn.
• Tom Conway, who played the villain, Medford, was brother of actor George Sanders. Sanders, was at one time  married to Benia Hume (Tarzan Escapes). After the peak of his long career he committed suicide.
• ERB forced MGM to take out a scene where Tarzan threw back his head and laughed loud and long at the treasure hunters. Such behaviour was not in keeping with Tarzan's character as created by Burroughs. 

Motion Picture Herald
Again he swings through the trees with the greatest of ease does Tarzan and this time his son does likewise, but with even more ease and abandon do the writers of this stanza swing through the stratosphere of imagination accompanied by a technical crew which makes a multitude of impossibilities seem plausible enough for the juvenile trade of all ages... Produced by B. P. Fineman with no sparing of the budget and directed by Richard Thorpe, the film stacks up as about the best of the Tarzans.

Variety
Latest adventures of Edgar Rice Burroughs's superman of the African jungle are detailed in tune with the wild imaginings of the author to catch attention of the juvenile trade and still provide opportunity for adults to laugh at the fantastic antics of the Tarzan family without restraint. Picture is a par entry in the series, which Metro spaces judiciously to overcome objections to the cinematic flights of fancy. Early section of the yarn displays the usual animal stuff, with comedy antics of the pet simian, Cheta, providing elemental laughs. There are several underwater swimming episodes to display the aquatic prowess of Johnny Weissmuller, also there's the usual jungle family life of the Tarzans. The secret treasure turns out to be gold, which is plentiful among the rocks of the high escarpment on which the Tarzan group lives. After Tarzan saves a band of explorers and scientists from the nearby savage tribe, the expedition is guided up the escarpment on a short cut across country. Greedy members of the band figure to move in on the golden hill, but are routed by Tarzan and a savage tribe that captures the expedition with aid from a herd of elephants and peace again comes to the Tarzan hideout. Picture swings into straight meller for the second half, with several sequences devoted to miraculous escapes by Tarzan from death. Latter events are to be expected from the jungle miracle man, to pass muster with audiences who have become familiar with the Tarzan character in print and film. Weissmuller adequately handles the Tarzan role in his usual style, with Maureen O'Sullivan as his jungle mate and John Sheffield their offspring. Miss O'Sullivan carries quite an English accent into the jungle, which is apparently throughout. Barry Fitzgerald, member of the expedition, carries the comedy assignment in the latter portion to good advantage. Others in support include Reginald Owen, Tom Conway, Philip Dorn and Cordell Hickman. Direction by Richard Thorpe injects a good pace to the script, turned out by Myles Connolly and Paul Gangelin. Jungle setting is familiar background for previous Tarzan adventures, while camera work by Clyde de Vinna and process special effects by Warren Newcombe are good contributions.

The New York Times
God Rest ye, merry gentlemen, let nothing you dismay and especially the current offering at the Capitol, which is just another Tarzan film, that's all, and not an anthropologist's nightmare, as a serious person might suspect. Metro calls it "Tarzan's Secret Treasure," and that's as good a title as any, for it tells in truly comic-strip hyperbole of a shockingly outrageous attempt by a couple of greedy scientists to ravish the ape-man's paradise of its gold. And it concludes in the customary fashion with Tarzan conscripting his faithful friends, the beasts, to put the outsiders in their places and to save his African solitude for himself, his mate and his youngster, who has grown to be quite a lad.   Don't let it throw you, Christmas revelers. It is all in the spirit of fun. And although there is nothing about it which would distinguish it from other Tarzan films and save the introduction of Barry Fitzgerald as a kindred soul in the wilds and the fact that Johnny Weissmuller has added a few words and his vocabulary to the animal scenes, especially those which star a chimpanzee, and the fanciful concept of the whole thing is, as usual, pleasantly lacking in guile. Obviously, the Capitol is playing to juveniles this week. - Bosley Crowthers