Walt Disney screened the movie because he was interested in casting James Arness as Davy Crockett. However, he was so impressed by Fess Parker as the "Crazy Texan Pilot" that he chose him for the part.
Because of their height difference, James Whitmore was forced to wear lifts in his shoes to make it appear that he was the same height as James Arness.
In 1998, Joan Weldon revealed that during the shoot of Them!, the temperature reached 110°F and both she and Edmund Gwenn were wearing wool clothing. It was even more insufferable for Gwenn, who struggled with advanced arthritis. Although unnoticeable to audiences, he was in pain and was helped off set by his valet.
It was also supposed to be in 3-D. Some elements of the 3-D effects, such as the ants having extreme close-ups and the flame throwers shooting straight into the camera, were used in the film.
Relating to the "S.S. Viking" incident, there was no cruiser named "U.S.S. Milwaukee" in commission in the United States Navy at the time this film was made. The last ship so named was an Omaha-class light cruiser (CL-5) which was commissioned in 1923 and scrapped in 1949 after service in World War II in both the U.S. and Soviet navies. The next ship named "Milwaukee" would be a Wichita-class replenishment oiler (AOR-2) that would be in service from 1969 until her decommissioning in 1994. Her name was stricken from the Navy's list in 1997, and at the time of this writing (2007), she is awaiting final disposal at the James River Reserve Fleet, Fort Eustis, VA.
Shortly after the helicopter reconnaissance, a meeting opens with an army officer looking through a Stereo Realist red button viewer. He is evidently looking at 3-D slides taken by Dr. Pat Medford. A second viewer is on the table next to Dr. Medford. This was rather clever product placement, considering the film was originally slated to be shot in 3-D format.
The B-25 Mitchell bomber transporting the doctors Medford was actually the personal transport for a 2-star General.
The camera Dr. Pat Medford is using in the helicopter is a Stereo Realist, which is a 35mm format stereoscopic (3-D) still camera. This is both perfectly natural and ironic since the film itself was originally planned as a 3-D release.
The flamethrowers used in the movie were standard World War 2 weapons and were loaned by the US Army. The actors handling the weapons were WW2 combat veterans who had actually used them in battle.
The sound that the giant ants from "THEM!" make as they approach their prey is a recorded chorus of bird-voiced treefrogs (Hyla avivoca) of the southeastern United States. Occasionally a grey treefrog (Hyla chrysoscelis) can be heard on the soundtrack as well, as these species can often be heard together at the same wetland.
This was Warner Bros.' highest grossing film of 1954.
Unique script that begins as a standard police murder mystery and ends as a science fiction classic.
Was originally supposed to be filmed in color. Two days before shooting began, a nervous studio cut the budget, and the film had to be made in black and white. However, in the opening credits, the title is shown in bright red against a black-and-white background.
When this movie was first released in Sweden, it was strangely named "Spindlarna" (which translates as 'The Spiders')
WILHELM SCREAM: Can be heard four times in the film. When the giant ants attack the crew of the ship at sea, when James Whitmore's character Police Sgt. Ben Peterson is throttled to death by a giant ant, when a soldier is struck by the falling debris in the sewer and when James Arness gets separated from the rest of the Army and ants try to attack him. The ceiling falls in and while he reloading his weapon, an ant tries to attack him. There's also a scream off-screen from Peterson's partner, Ed Blackburn when he investigates the sounds made by the ants.
Leonard Nimoy: the soldier who reads the wire copy story about the pilot being held in a mental hospital in Texas.