A grandstand call in basketball refers to a very important call that requires all on-court officials to determine the outcome of the call. This could be an instant replay review or determining whether to throw a player out of the game.
Grandstand calls are often controversial or difficult to determine. If the first referee who rules on the play seems to rule incorrectly, the other referees may gather to discuss the call. If the referees can not come to a conclusion together, they will likely turn to video review, or instant replay, technology.
To determine the ruling of certain game situations, referees can use instant replay technology. A few things that can be reviewed are buzzer beater shots (if they were released in time), out of bounds, if a shot was a 2-pointer or 3-pointer, and the time on the clock. Many other types of plays can be reviewed.
Many plays can not be reviewed, which will often frustrate the fans of the team who was wronged. One limitation of instant replay is that referees may only rule on what they were reviewing. This means if they go looking for one thing on the replay and find another call that they made incorrectly, they can't fix this mistake.