Considered to be the first film to deal with the concept of time travel.
Generally considered to be the cinematic debut of the dinosaur Tyrannosaurus rex, or at least its first appearance in a film that still survives. Since most silent films of the early 20th century are lost to time, it is unknown if T. rex had any prior appearances.
This was Willis H. O'Brien's first film after the split-reelers he had done for Edison's Conquest program.
The design of the Tyrannosaurus was ahead of its time. It predates the first Tyrannosaurus painting of artist Charles R. Knight, the world's leading paleoartist of the time by a year, and it is also more scientifically grounded. It has robust leg muscles to support its weight, whereas Knight incorrectly reconstructed the animal with thin, lizard-like legs due to his personal belief that dinosaurs were "imperfect" creatures destined for extinction. The film also portrays T. rex as an active but cautious hunter, which would become the accepted scientific thinking in the late 20th century, while many western scientists at the time of the film's production falsely thought of it as a sluggish, dimwitted creature. It also has lips to protect its teeth when its mouth is closed, a detail that gained wide scientific support during the 2010s, a hundred years after the film's debut. Outdated elements of its design are the upright posture, the tail dragging on the ground, the dewclaw reaching the ground and the mammal-like prehensile tongue, however these were commonly accepted at the time.