When Norman is leading June into Lucy's office, we can see Lucy's reflection look up and watch them come in. However, when the shot moves to Lucy, she is still wiping off the front of her shirt, and has no clue they have come in until Norman gets her attention.
During the Charity Ball, June is wearing a sheer, almost see through dress. As June and Wade enter the elevator, during the elevator scene and as they enter the apartment, you can see June's areolas through the top. Then, when Lucy comes into the apartment and catches June in a state of near undress, she is now wearing a opaque solid black strapless bra. She could not have been wearing that particular bra in the previous scenes.
When Norman brings June into Lucy's office for the first time, you can see Lucy's reflection in the windows but it's as if the windows behind her are blacked out so that the camera and equipment wouldn't be seen. When the shot is changed, the windows are open and bright.
While George and Lucy are driving from the tennis club, there is a UPS truck following 2 cars behind them. When they head up a ramp, we don't see the truck follow but in the next shot, it's there again. It is gone again when they stop in the traffic jam.
When George is talking to June in the coffee room, right before he asks her to come to the benefit, George is shown holding a coffee pot in his hand. When he turns around to ask June to come, he's holding a milk carton. After he asks and turns again, he's holding the coffee pot again.
While on Coney Island to promote the construction of the new community center, George and Lucy can be seen wearing wellington boots. In the following long shot we see them walking away with Lucy's parents and George is wearing street shoes.
When Lucy enters the elevator at the Grand hotel after leaving the wedding, she is wearing one glove - on her right arm. When she comes off the elevator into George's suite, the glove is on her left arm and the right arm is bare.
When Lucy and George are in the shop, Lucy is standing there with a pile of clothes over her arm. There's a red jumper on top of the pile. In the next shot the red jumper disappears and then reappears in the next shot.
During the wrecking ball scene, the purple mat on Lucy's backpack is rolled differently in almost every shot. Sometimes its rolled loose, other times its rolled tight, sometimes one way, sometimes the other.
At Lucy's farewell party we first see a shot of the cake which is almost entirely whole; only a few slices have been cut. But when we see the party guests, all of them have large pieces of cake which obviously could not have come from the cake we can still see in the background.
When George and June are at the charity ball, June is wearing her black dress and top hat, and her red hair falling below the hat is in tight spiral curls. Later as they are riding up in the elevator with the older couple back at the hotel, her curls are visibly much softer compared to before. When Lucy interrupts them a short time later in George's suite, June greets her in her top had and lingerie and her tight curls are back.
When Lucy enters the hotel, the clock show 36 minutes past the hour. When she walks out, having traveled upstairs, walked in on George and June, and come back down in the elevator, the clock in the lobby says it's only 40 minutes past the hour.
When George meet Lucy's parents for the first time and they invite him over for cake because they only live two blocks away you can tell it's over a mile. When they start leaving the construction site there is a large tower they start walking towards with a large construction crane about 1/2 a mile past it on the right. However, immediately when they get to the apartment roof, you can see the crane below about 1/2 a mile up the beach and the tower is over a mile away now.
As George and Lucy are walking towards the RV while stuck in traffic on the overpass you can see a white lane line dividing the two directions of travel. A white lane line between two lanes indicates both lanes are in the same direction of travel - a yellow line would indicate opposite directions as attempted here.
When Lucy and George are flying around Manhattan in the helicopter they are clearly not actually flying because the lighting on their faces does not change as the helicopter rotates and flies between the skyscrapers.