Plot hole: When George stops the machine for the first time, the candle burned down to about half of its size, which took according to his observations 98 minutes. But as the trip continues it takes seven hours for it to burn down completely. (00:25:45)
Factual error: In 1917, James Filby has driven and parked in the wrong direction in front of Filby's Department Store. (00:33:08)
Continuity mistake: When George stops in 1917 he kicks some planks from a fence that has 4 small signs and a plank missing, in the next shot 3 signs are gone and the missing plank is reattached. After he talks with Filby Jr. he climbs back through the original fence (the one with the missing plank and 4 small signs, plus 3 other ones that were out of sight in the first shot). (00:34:00)
Revealing mistake: During the big underground fight scene, the solid rock wall moves as George pounds a Morlock's head against it.
Continuity mistake: The Morlocks aren't affected by the light from metal in fusion in their foundry but they recoil from the light of a match.
Revealing mistake: George is underground fighting the Morlocks and kills several of them. As he leads the terrified and apathetic Eloi out and back up the ramp, one of the dead Morlocks very thoughtfully moves his legs out of way.
Visible crew/equipment: During the campfire scene a Morlock attacks Weena, and drags her off. If you look at the top of the frame, as the Morlock drags her away, the stunt man's head can be seen, as he forgot to wear the head part of the costume.
Other mistake: When encased in rock, George lights a match to see the current time dial on his machine. But the dial is backlit every other time its shown.
Plot hole: In 1966 when George is about to return to his machine and the atomic bombs (or whatever) go off, George just barely gets out of there before the lava from a nearby volcano cooks him alive. Two plot holes here. One is that in the short time it takes George to walk a few meters to his machine, a volcano explodes and the lava reaches him. Thats very speedy lava..especially considering there were no mountains near George's house. Secondly when the lava approaches, it is just flowing along the ground like normal. But when it reaches George, it splashes around him like a broken water tank. That lava can certainly defy gravity.
Continuity mistake: When the time traveler is first starting to travel in time, the sun moves across the window from left to right, indicating that the window faces south. When night arrives, however, the view is of the stars moving right to left, indicating that the window is facing north.
Continuity mistake: When the time machine is traveling through time, close up shots of the control panel show the light bulbs flashing in exact synchronization with the time display. In far off shots of the time machine, the light bulbs are flashing more slowly.
Continuity mistake: When Rod Taylor is thrown by the Time Machine in the future, you can see dry ice pellets fall and hit the ground from the top of the screen, and he is not in this scene. Next shot you see him lying flat on on the ground with a little bit of fog around him.
Revealing mistake: When the time-traveller enters the Morlock caves via the ventilation shaft, you can see (when the screen is bright) that the background of the cave behind the machine section is merely a painted screen.
Revealing mistake: As George comes to the year 1917, the camera shows that the buildings in the horizon are nothing but poor painting, especially on the wall around the archway. The two buildings right beyond it have distinct differences above and below the top of the archway.
Factual error: As the machine is traveling through time George becomes aware of "strange sounds" which, when he stops, turn out to be air raid sirens. At the speed at which he was traveling through time, the sirens would have had to operate continuously for several days in order for him to have been able to hear them.
Factual error: The time traveller can hear external sounds in his machine, which means that vibrations outside of his machine's bubble of space can penetrate it. If this were true however, the machine would be destroyed in mid-travel by the shockwave of the nuclear blast.
Continuity mistake: When the Time Traveler is almost overpowered by the Morlocks, there is a shot of the torch which was whipped out of his hand. It has nearly burnt down, but as he regains it and orders the Eloi to escape, it burns strongly again.
Visible crew/equipment: At the end of the movie when they're escaping the morlocks, one of them catches on fire - he is obviously wearing a fire protection suit, since he is immensely fatter then the rest of the morlocks.
Continuity mistake: At the very end of the movie, when Mr. Wells' housekeeper bids Mr. Filby goodnight, watch how quickly the upstairs lights get turned off after the downstairs lights. Considering that the time traveller was gone and she was the only one left in the house, that old woman must have RUN up those stairs faster than any human being could...
Factual error: When the machine is in the laboratory racing through time and the sun whizzes across the window, note that the clouds don't move or change formation throughout the entire 'day'. In reality, clouds can change and move dramatically in only minutes.
Answer: Earlier in the movie, Mrs. Watchit hands an envelope to Philby with a note inside to inform everyone that if George doesn't show up at 8:00, then they can start dinner without him. This is what he most likely left on the mantle before he started his journey through time.