When Maria is running through the house holding the gun, it disappears and reappears repeatedly.
When Lara is in the hot tub taking selfies, the first few she takes she's holding her phone in the vertical position. When it cuts to her looking at the photos, she's holding her phone horizontally. Cut back to her taking more picture, she's holding the phone vertical again for a couple seconds before finally rotating it to the horizontal position.
The masks will occasionally rise on Pooh and Piglet, exposing the faces of the actors underneath.
At 48:40, when Piglet is swinging the heavy chain into the pool, the chain floats as the character pulls it back. Chains do not float on water unassisted.
The revolver only has one bullet when it should have been loaded with six.
When Lara is in the hot tub and gets her phone to take selfies, her phone case says 'Natasha', which is the name of the actress who plays her.