Callback (comedy), a joke which refers to one previously told
Callback (computer programming), callable (i.e. function) that is passed as data and expected to be called by another callable.
Callback (telecommunications), the telecommunications event that occurs when the originator of a call is immediately called back in a second call as a response
Callback verification, a method for e-mail address verification used in SMTP
Web callback, a technology that provides telephone callback for websites
"The Callback", an episode of the TV series Smash
Callback, in the performing arts, a stage of the audition process