Do airlines have freezers?
(Source) Cool room in a cargo terminal.


  The rabbit arrived fine but there was some sort of mistake and he was locked inside a freezer overnight.


Goods that are perishable and human remains awaiting transport, wait in the freezer before being loaded onto flights.

Different rooms for cargo handling can be seen here, they include:


Cool rooms
Freezer rooms
Warm rooms (for e.g. perishable flowers)
Dangerous goods rooms


There are also specialized ULD's that come with refrigeration units.

(Source) Temperature controlled ULD.


  [Depending] on the nature of the goods to be transported, [ULD's] may have built-in refrigeration units.