In the opening shot of the street outside George's house, the post-box bears the initials G.R. British Royal Mail post-boxes bear the initials of the reigning monarch at the time they were installed. G.R. indicates King George V, who did not become monarch until 1910 - some 10 years after the scene is set.
When George arrives in 1966, he hears the sound of an air-raid siren and decides to stop and investigate. However it takes him several days to bring the machine to a stop, and the siren can be heard continually for about three days.
When George returns from the future, as he is breaking into the conservatory, a clock is heard striking the hour, but at the same time, a clock inside the conservatory shows 8:03. George wouldn't have allowed any of his clocks to be that inaccurate.
When George enters the laboratory for the first time, he shuts the door and locks it. Rod Taylor must have cut his finger on the lock because as he approaches the Time Machine and touches the brass rail at the control panel he leaves a streak of real blood.
When George arrives at the Pyramid, before walking off, he takes the crystal control lever and puts it in his front pants pocket, clearly creating a large protrusion. The protrusion disappears until it's time to restart the machine.
When George is first traveling in to the future, we see Mrs. Watchett in fast motion walk down the street, look in a shop and walk away again. But at that point, George was already traveling at a lot faster rate (at least 1 day per second).
When the atomic bomb explodes in 1966 London, all the buildings, cars, etc., are instantly incinerated; but in close-up George is shown lying flat on perfect, unburned green grass, unscathed, and the time machine is equally undamaged, sitting undisturbed beside blossoming, untouched foliage.
When George is in the laboratory and is starting his voyage, you can see the sun and moon race across the sky through the overhead windows as they display the rapid passage of time. These windows also contain the winter frost around the edges of the panes of glass from the January 1900 winter. But throughout the rapidly changing years and seasons, the frost remains in place, never melting and re-appearing each winter as it should.
When George is the near the Morlock statue, he looks up and the sky is nearly dark as it would be at sunset. He sees movement in the bushes and pulls Weena out. At that moment, you can see the sky again and it is bright as it would be in broad daylight.
Immediately before entering the chimney to the underground Morlock cave, George drapes his jacket over the chimney rim. Later, when he's escaping with the Eloi via this same chimney opening, his jacket is no longer where he left it, nor is it on the ground.
When George is putting his coat on Weena after rescuing her from the river rapids his hair is very wet and water is pouring from it. In the next close up sequence his hair is less wet and even little but fuzzy. His hair is again very wet in the next frame when Weena gets up and walks towards the Eloi.
In the first scene of the film, when Filby enters George's house, the gas chandelier in the entryway is fully lit. However for the rest of the scene it is completely dead, and remains so until Mrs. Watchett comes in at the end of the scene to light it for the night.
In the laboratory, George reaches up on the control panel near the lights and flips three switches, then flips one more switch near the bottom. When seen from the chair, the control panel has no switches.
Towards the beginning of the film when George is demonstrating the miniature Time Machine, the first close-up shot shows the disk-like device at the rear of the machine rotating counterclockwise. The next close-up, the disk is rotating the opposite direction. In the final close-up (just as it begins to disappear), the disk is again rotating counterclockwise.
When demonstrating the miniature time machine, George takes a cigar with a pointed tip from the doctor and places it into the model. In the close-up when the miniature is about to disappear, the cigar has a blunt tip.
When George runs back to the woods in frustration, it is evening. Then when he arrives and discovers the Morlocks have dragged his machine inside the Sphinx, it is daylight. Then, when he notices the movement in the bushes, it is nighttime.
During the fight scene with the Morlocks, just after one of the Eloi hits a Morlock over the head and George kicks it against the wall, where it begins to bleed from the mouth, George looks over at his torch and it is almost completely extinguished. However, when he retrieves it seconds later, it is burning brightly again.
When sitting on the stairs, Weena looks to her right, apparently to the setting sun. But the shadows she and George throw indicate the sun is to Weena's left. In the next shot, when they walk upstairs to the hall, their shadows are much shorter, indicating noon.
After George discovers the Morlocks have taken his machine inside the temple, he and Weena gather sticks to make a fire. He throws several pieces of wood on the pile while Weena is sitting there. One of the pieces sticks out of the pile against her dress and in the next scene, the wood is no longer sticking up.
At the beginning, when the group of friends is waiting for George to show up for the dinner appointment, Filby is sitting in front of a clock that reads about four minutes to 8 pm. Suddenly all the other clocks in the room, which read 8pm, start to clang and gong. When the camera comes back to Filby (only a moment later in move time), the clock behind him reads 8pm, too.
Near the end of the film, when George is traveling back to his own time, we see the time gauge go back 100,000 years per two seconds or so. Then, when George gets to the atomic war, the mountain around him turns back into liquid rock and vanishes. Over the course of several seconds, we see the surrounding landscape on fire as a result of the nuclear bombs, indicating it's the same day. Then we see the time gauge go from 1966 to 1962 for about one year per second. George had not pushed the lever forward or backward since leaving 802,701.
When George starts time traveling in his lab, we see the sun and moon cross his field of view. But then we see stars circling Polaris in the same area. Polaris is nowhere near the ecliptic (path of the sun).
When George's friends leave his house after the demonstration of the miniature time machine on December 31, 1899, it's a few minutes before 6:00 by all the clocks in George's house. (Most noticeably, the clock on the table that George leans on by the window as his friends put on their coats.) We see his friends leaving and getting into a carriage in broad daylight, but it is pitch dark in London at both 6 AM and 6 PM on New Year's Eve.
After the 1966 atomic explosion there is a volcanic eruption. There have never been volcanoes in the British isles since they are nowhere near a tectonic plate boundary. Therefore an atomic explosion would not cause an eruption.
Wells travels 800,801 years into the future yet he and the Eloi speak the same English. Studies at several universities have shown that language evolves at such a rate the people separated by less than 1000 years could not understand each other.
In the opening clock montage, the hands of Big Ben are shown in an impossible position. The minute hand is on the half hour yet the hour hand is directly over the seven. It should be midway between the seven and eight.
When George arrives in London in 1966, all the vehicles are left-hand drive. British vehicles are right-hand drive. This is due to the fact that the live action scenes were filmed in Culver City, California.
When George first goes into the dome you can see him looking around and down where he picks up a marker on the floor where it is visible when he goes to leave. It is an X marked with chalk on the floor.
After a Morlock tries to drag Weena away and George stops him, George says that they will start a campfire to keep the Morlocks away because its light hurts the Morlocks. He has no way of knowing this as he has not used his matches in front of any Morlocks yet and seen them react. He will not do this until later when he is in the Morlocks' lair to free the Eloi.
When George discovers that the Morlocks have moved his time machine, it is late afternoon or twilight on the same day he arrived. The light-fearing Morlocks would not have come outside to move the machine until after dark.
In the great hall whenever George is inside, you see parallel and perpendicular white lines painted on the floor. The table arrangements do not conform to any arrangement that fits these lines. This is because the set was constructed over a studio parking lot and they did not put down a floor covering. The revealing parking lines are simply ignored. This info came from a special effects veteran who was on the set during the filming of these scenes.
As George approaches the year 802701, just as the wall behind him is completed, the background plate is missing for one frame which shows, instead of the wall, some scene number writing (the words "back frame") and the tip of a thumb. This is not visible at normal speed because the scene is 'flashing' to show the rapid passage of day and night, but on the MGM DVD and laser disc, the frame can be isolated.
When George begins his traveling through time, the rate at which the sun and stars move shows he is watching the passage of a day in less than a minute of his own time. However, without changing the rate of travel, he sees people moving around in front of the shops across the street, staying there - at his current rate - for hours.
When George suddenly stops the time machine in year 802701 the machine spins out of control throwing him out onto the ground. As George lays unconscious you can see "dry ice" being dropped from above near George's body to produce the smoke effects rising up from the grass.
When George rescues Weena from drowning, the current at the large rock is a raging torrent. But in the next shot as he is pulling her to safety on the other side of the same rock, the water is very calm.
When George restarts the machine after looking at the mannequin and saying "Good heavens, that's a dress?", he is traveling slow enough to be able to see the store owner changing the mannequin's clothes, yet the light outside the store is shown flashing on and off several times, indicating that several days are passing.
While George is first traveling in to the future, we see the trees blossom with fruit over the passing months, but the plants in the background remain the same length and don't even move, as does most of the foliage when we see out to the garden as the years go by while George is narrating "13 years had passed..14..15..16..."
In a wide shot in the 1966 scene, a guard in the middle of the frame partly vanishes as he steps backwards (just before the dark-colored Jaguar arrives from the left). This is because the street shots in this scene as well as in that of 1917 are pasted together from different shots and matte backdrops. As a matter of fact, the perspectives don't even match (different angles).
When George time travels back near the start of the film to enter his then dusty former home, he has to unlatch his laboratory door first to enter the rest of the
house. The glass and wooden doors out of the lab are locked from the inside.
But at the end of the film, Filby breaks through the latched lab door moments
after George left in the machine. There would have been no latched door in the
future for George to undo.
(At 39:10 - 39:13) During the Air Raid in 1966 London, as the Jaguar XK 150 drives up, its shadow is visible on the right half of the screen before it arrives at the line dividing the two sides of the screen.
In the exterior scenes at the beginning outside George's house, on New Year's Eve 1899, with snow on the ground, neither the characters' nor the horses' breath is visible as condensation, as it would be in cold weather. (This is a special effects problem that never was solved prior to digital effects.)
The dial plate of the equatorial-type sundial outside George's house is not oriented correctly. It should be parallel to the equator, but the direction of George's shadow (when he is outside the house in 1917) indicates otherwise.
Several times in the background during the hall scene, when the Eloi drink from the large white cups, apparently the cups are empty. However the two Eloi seated to the right of George definitely have something in their cups, the liquid can be seen sloshing on the inside of the translucent cups.
Although the model is said to be a smaller version and fully functional, it differs prominently from the full-scale time machine in various technical details, i.e. the curled wires behind the seat are missing (for that matter, regardless the question if curled cable was available in 1899).
The goof items below may give away important plot points.
At the end of the film, after Filby leaves George's house and Mrs. Watchett shuts the front door, the house is shown in long shot with one light lit downstairs and two, in two different rooms, lit upstairs. Almost immediately, the downstairs light goes out, then in rapid succession first one, then the other, upstairs light. There is no way anyone, let alone a 62-year-old woman (as Mrs. Watchett was said to be), could have possibly shut off three different lights, in three different rooms on two different floors, in the space of approximately five seconds - not to mention the fact that she was fully dressed when she shut the door a few seconds earlier and couldn't possibly have gone to bed in that time either.
At the end of the film, Filby re-enters George's house, and as it's snowing, there is snow on the shoulders of his overcoat even at the point where he breaks into George's laboratory. However, on entering the room, the snow has completely disappeared from the coat, which is not even wet.
As George is returning to his own time, we can see him grasp the control handle as he slows the machine down to a stop in 1900. But in interspersed close-ups of the machine's control panel, the handle is visible at the far right without George's hand on it.
George was watching the fashions change on the mannequin, the windows got boarded up, and he got out to talk with Jammie's son. The mannequin is wearing an outfit with fur around the hem, a long strand of pearls, and what appears to be her white gloves draped over her right arm. You can see her twice, first as he walks away from the shop, back toward his house, and then again as he tears down a few of the boards covering the window to his laboratory. It is also evident that she is standing in front of a tan fabric banner, draped across the display window opening behind her. George then walks around to the front door and into the house. As he gets into the time machine, we see the mannequin for the last time, but she is now missing those gloves and the fabric banner has changed from tan to purple. There are bolts of fabric stacked in front of her, to the left, that also have been changed.
After George stops suddenly in 802701, the time machine starts rotating. During the first rotation the year the time machine says is actually January 5, 1900, which is the date that he returns to the present time at the end of the movie.