Below is an example of three dead hands without a Mah Jongg in error: 

1. Player A has too many tiles.

Outcome: Player A’s hand is declared dead and they stop playing. Play continues with Players B, C and D.

2. Player B has too few tiles. Play continues with Players C and D.

Outcome: Player B’s hand is declared dead and they stop playing.

3. Player C has an invalid exposure.

Outcome: Player D declares Player C’s hand dead and all hands are thrown in.

Source:  Mah Jongg Made Easy, 2020, page 17, 4e
http://www.nationalmahjonggleague.org

See ID123, Mah Jongg in Error Examples
See ID78, Reasons to call a Player’s hand dead