When Thomas is driving along Stockwell Road towards Woolwich, he drives past the same red-painted building - Pride & Clarke (a contemporary motorcycle dealer) - several times.
When Jane first confronts the photographer in the park and tries to stop him, her hairstyle keeps changing from brushed straight back to hair parted.
When Jane tries to sneak out of Thomas' studio/home with the camera, her hairstyle radically changes from the way it was upstairs to a different style when he stops her. When they go back upstairs, it's back to the old style.
When Thomas purchases the propeller, he is shown displacing a few bust sculptures from a shelf above. In the next shot, they are back in perfect order.
In on the bushes - whilst filming the couple in the park - Thomas (David Hemmings) has accidentally started the self-timer on the Nikon F.
The overdub shutter noises continue even though the camera wouldn't be able to take a picture until the timer had expired.
David Hemmings' character uses a two-way radio from his Rolls several times in the film. This was very rare for 1966 and a precursor to the car phone. However, mobile radios like that at that time need a large whip antenna attached to the car to function. The Rolls has its normal radio antennae on the fender, but nothing else so that two-way radio could not work.
Actually, there is a whip antenna attached to the rear bumper; it is seen in several shots of the car.
When Jane gives Thomas her phone number, there is a huge piece of coiled-up hair at the bottom of the screen.
The hawthorn is in bloom in the park one day and entirely missing the following morning, though still in full leaf. It is clear that the second "day" was filmed in midsummer, some weeks after the first.
When Thomas is frolicking with the two girls on the purple paper backdrop in the studio, two crew members, including a camera operator, can be seen just sitting there in the top right side of the frame.
Shadow of camera crew visible when the photographer is driving home from the factory.
When the photographer gets out of his car and walks towards the telephone box, for a split second a crew member's arm is visible behind the wall on the right of the shot.
Reflection of bald man with glasses in the top right corner when Thomas is in the phone booth.
When the mimes stop Thomas in his car at the beginning, the entire film crew is reflected on the side of it in the shot from behind them. When it returns to the view from the passenger side, an old man is walking by on the other side of the street.