When Miles is lighting the candle with the match around the one hour mark it is obvious that the flame of the candle is being used to light the match and not the other way around.
When Grandma Anna kills Dr. Goodbery in the attic she goes from being covered in blood to having no blood on her in the next shot.
After the Midnight Man leaves Miles, at the 50:24 mark the candle is lying on its side. Before he gets the matches out of his pocket, he puts the candle upright. After he gets the matches, the candle is shown on its side again.
The rules of the game clearly state that all the lights in the home need to be turned off,yet when Alex first enters her grandmothers bathroom,there are lights on in the bathroom.
One of the rules to joining the game is to light the candle, take it outside and blow it out, then light it back inside the house. Kelly does not do this, therefor she is technically not officially part of the game.