Sally Sparrow is in the house, she sees a key hanging from the angel's hand and goes forward to take it. First we see the front shot and the string is looped around the angel's hand. Cut to side shot and the string is hanging with no loop. Front shot again and the loop is back. Side shot where she actually takes the key and no loop. The position of the string may have been altered during shooting as having Sally unravelling the string to get the key would have taken several seconds and she really wanted to be out of the house as fast as possible.
Throughout the episode the speed of the Weeping Angels varies dramatically. The Doctor describes them as "faster than you could believe" and in one scene they are apparently able to cross from a building on one side of the street to one on the other side in the time it takes a character to blink. In the rest of the episode however they show an inability to cross a small room in a similar time frame.
When Sally pulls the wall paper off, part of the year (1969) gets pulled off, but when she comes back with Kathy, all parts of the year are written on the wall.
During the sequence where Larry is confronted by one of the Weeping Angels, the position of its left arm keeps changing despite him constantly staring at it.
(13 minutes in) When Sally enters the DVD store the clerk puts his finger to his lips but in the next shot his hand is away from his mouth. It then cuts back and his finger is on his lips again.
In the entire episode the weeping angels have grey eyes. Just before Sally gets out of the circle, you can see the actual eyes of the actor who plays a weeping angel.
The footage of the doctor speaking that was put on the DVDs was supposedly shot in 1969 but instead of looking like film footage it is clearly some kind of video: the texture, the colors, even the frame rate, nothing feels like it was shot in 1969. They even added some stains and scratches but that only made it look even more fake.
While Billy Shipton is showing Sally Sparrow the TARDIS (in the room where he keeps the abandoned cars), just after he says, "[You] can't even get in it'", he rattles the TARDIS' handle to demonstrate. Watch carefully: When he shakes the handle we hear a rattling noise as if the door is shaking, but in fact the door stays rock solid.
When Sally Sparrow and Larry Nightingale are confronted by the Angel and Sally tells Larry not to take his eyes off the angel, after Sally runs out of the room you can see a crew member walk up to the door before the scene changes.
The house has been abandoned for years but still has electricity.