Is there a penalty for calling a false Uno?

If [the player with one card is] caught not saying “Uno” by another player before any card has been played by other players, the player must draw two new cards. That rule does not establish a penalty for incorrectly “catching” another player not saying Uno.

Do you keep drawing in Uno If you don’t have the color?

According to UNO, there’s no need to draw countless cards until you get a colour or number that matches the Discard pile. You only have to draw ONE, and skip your turn if you can’t play that card. “If you don’t have a card that matches the one on the DISCARD pile, you must take a card from the DRAW pile.

Can you put a draw 4 on top of a draw 2?

Players are not allowed to stack Draw 2 and Draw 4 cards. If someone puts down a +4 card, you must draw 4 and your turn is skipped. You can’t put down a +2 to make the next person Draw 6. Upon reading, the teacher discovered players are only allowed to play the ‘Draw 4 Wild Card’

Can you put a plus 4 on a plus 4?

No, it’s not valid to do so since according to the Mattel’s UNO rules the next player forfeit their turn and MUST draw 4 cards from the pile. So in that case you could say that a Wild Draw 4 Card could be played on a Wild Draw 4 Card. Remember that it’s only the next player who can make the challenge.