[2] Callender represented Trinidad and Tobago at the 2008 Summer Olympics in Beijing.

He competed at the 4 × 100 m relay, together with Marc Burns, Aaron Armstrong, Keston Bledman and Richard Thompson.

Their time of 38.26 was the fastest of all sixteen teams participating in the first round and they qualified for the final.

[3] At the 2012 Summer Olympics, he raced in the first round and the final, and Trinidad and Tobago won the silver medal.

[4] Callender set new personal bests in the 100 and 200 meters at the Grande Prêmio Brasil Caixa meet in May 2009, recording times of 10.16 and 20.40 seconds respectively.