During the summers, Casey worked several odd jobs to support himself, including coal mining and tobacco farming.

[8] In late March 1988 while still serving as an assistant coach at Kentucky, Emery Worldwide employees discovered $1,000 in cash in an envelope that was accidentally opened.

During his time there, Casey coached for Sekisui Chemical and Isuzu Motors Lynx that his teammate Jack Givens played for.

[7] Casey left the Japanese Basketball League in 1994 after receiving an assistant coaching position for the Seattle SuperSonics.

At the beginning of the 2005–06 NBA season, Casey landed his first job as head coach for the Minnesota Timberwolves, replacing Kevin McHale.

LeBron James of the Heat would later admit that Casey's defensive schemes for Dallas helped make him improve his game even further after that series.

[19] On November 1, 2015, Casey surpassed Sam Mitchell's franchise record for wins, getting his 157th against Milwaukee Bucks with the score of 106–87.

[22] On May 1, 2016, Casey coached the Raptors to their first Game 7 victory in franchise history with an 89–84 win over the Indiana Pacers in the first round of the 2016 NBA Playoffs and on May 15, he coached the Raptors to their first appearance in the Eastern Conference finals in franchise history with a 116–89 victory over the Miami Heat in the second round of the playoffs, where they fell to the eventual NBA champions Cleveland Cavaliers in six games.

[27] Casey's Raptors set franchise records for wins and points in the regular season as they finished first in the Eastern Conference.

[28] Casey's conservative coaching structure and system was credited with developing the Raptors' younger players, however it did not fare well in the playoffs against the Tyronn Lue-coached Cavaliers who were flexible rather than being consistent.

[33][34] On November 14, 2018, Casey returned to Scotiabank Arena for the first time since being fired by the Toronto Raptors,[35] coaching the Pistons to a 106–104 win over his former team.

In the playoffs, the Pistons were swept in the first round by the Milwaukee Bucks, while Casey's former team, Raptors, won the NBA championship against the Golden State Warriors.

[40] During the summers, Casey likes to travel to Japan to help with basketball camps and coaching clinics.