Continuity mistake: After Danny gets mad at Walter for catching the ball that his Dad threw for him, he throws his glove down on the floor and runs inside. In the next shot the glove is in a different location.
Continuity mistake: After the ball knocks the glass of juice over, the juice spills all over a drawing that the Dad needs for work. Between shots the position of the spilt juice on the drawing changes.
Continuity mistake: In the shots before Danny throws the ball which knocks the glass over, the position of items on the desk keeps changing, and a computer mouse appears next to the glass of juice between shots.
Continuity mistake: When the Dad is playing catch with Walter in the front garden, in the first shot he is standing right in the middle of the lawn. In the next shot he is standing right beside the pavement.
Continuity mistake: During the meteor shower, the books on the shelves change position and the way they're stacked a couple of times, and the mess of books around the cabinets differs a few times as well.
Continuity mistake: When Danny throws the ball across the table at Walter, which knocks the glass of juice over, the ball also knocks a photo frame over. In the next shot the photo frame is standing upright again.
Continuity mistake: Danny has plasters on his right elbow. During various scenes, they appear and disappear. Also they once changed design. And around the end of the movie, the plasters disappear from his elbow and appear on his right hand.
Continuity mistake: In the opening scene, when Tim Robbins is playing catch with his son, the cars in the background keep appearing and disappearing.
Continuity mistake: When Danny gets up to go out of the room to get the baseball and catching gloves, after Walter turns off his game and puts the TV on, as he leaves the room, Walter's legs change position on the chair.
Continuity mistake: When Walter is watching SportsCenter, and Danny is complaining that he was watching SpongeBob, he changes his position between the a closeup of his head and a wideshot of him.
Continuity mistake: When Danny and Walter are in the kitchen, the zorgons shoot at them and blow out the kitchen windows above the sink. Later when they go back into the kitchen to start a fire to bring the zorgons back, Lisa goes into the kitchen and the windows are not broken. (00:40:00 - 01:07:00)
Continuity mistake: When Walter and Danny are trying to show Lisa what the Zathura game does, Walter lays the "Promoted to star ship captain" card on the game board in front of the card console. Two shots later the card vanishes. The camera had only changed for two seconds, so it's unlikely that either of them had enough time to take it away. (00:25:55)
Continuity mistake: Dad goes to wake up Lisa before leaving the house. She's sleeping on a pile of white pillows. A purple pillow later appears underneath her elbow before disappearing again when Dad leaves the room.
Answer: If you are talking about the part where Walter says that Danny cheated and Danny says "someone must have kicked the board", you're right, no one did kick the board. After again being asked if he moved the piece, Danny says "maybe I moved the piece by accident." I think this implies that Danny cheated and moved the piece himself, which is why it was on a different coloured space.
Except, it never showed Danny moving the piece at all. When Walter moved Danny's piece back to the space it was originally on, the game shot out a card accusing Walter of cheating and tried ejecting him out of the house. If Danny had moved the piece by accident and therefore technically cheated, it kind of raises the question as to why he never received a card accusing him of cheating and ejecting him from the house as well.
I think the answer to this is in the card's text - "Caught cheating" I believe this implies that since Walter was observed physically moving a piece by the other player, that is what triggered the cheating detection. Nobody saw Danny move his piece, so he was technically not caught cheating in the moment. So, ostensibly, one may be able to cheat as long as they are not caught by the other player.
Knever