Tapestry
After Era 4 has ended, can a tapestry card cover the Era 4 card, such as when Nuclear Bomb is reached on income turn 5?
Yes, under the Fantasies & Futures rules. Once you are past Era 4, a card effect that says to play a tapestry on top of the current one may cover the Era 4 card, taking effect immediately or for the current era as the card states. Under the original rules, no tapestry card is played after Era 4, so reaching Nuclear Bomb on income turn 5 plays nothing.