[3] While in college, Callender spent time with USL League Two side San Francisco Glens, but didn't appear for the team during the 2019 season.

[6] On November 12, 2019, Inter Miami acquired Callender's homegrown player rights from the San Jose Earthquakes in exchange for the 27th draft pick in the 2020 MLS SuperDraft, and potentially up to $150,000 in General Allocation Money if Callender were to meet certain performance-based metrics.

[7] Callender made his professional debut on May 7, 2021, starting for Inter Miami affiliate Fort Lauderdale CF against Union Omaha in USL League One.

[8] Callendar made six saves during Inter Miami's 2023 season-opening victory over CF Montréal, earning him a spot in the league's Team of the Matchday for week one.

[13] In August 2023, Callender received his first call-up to the United States senior national team by head coach Gregg Berhalter, for two friendly matches against Uzbekistan and Oman.