Canal Zone

(San) Cristobal: All the covers I've seen so far were back canceled with a Cristobal machine canceler

Cuba

Havana: Most of the mail for Cuba and beyond does not have the characteristic green Lakehurst Zeppelin back-cancel (but exceptions exist). When mail arrived in Havana, it received one or both of the usual Havana machine cancellations in use at the time. The predominant one being the airplane airmail slogan cancel depicted below. Besides this there was also a standard wavy line cancellation with a “1”.

Characteristic Havana airmail slogan

Wavy lines

There are some oddities in the Havana case. The mail was sent to Havana in two distinct batches. The initial batch (and probably by far the gross of the covers) is back canceled June 2, 1930. But one cover in my collection indicates that there must have been a later batch that carries the Havana cancel dated June 4^th!

Miranda, Oriente Province: A lot of mail for Cuba was created by or for Mr. John G. Kunz in Miranda, Oriente Province, Cuba, who had his own covers and acted as a go-between too. This correspondence carries the Miranda cancel.

The Miranda arrival cancel on the backs of the covers.

Haiti

Port-au-Prince: It seems that only Colson/Roessler covers seem to exist, in various forms. But the main hallmark of all these covers is that on the reverse one usually fins a Havana 2^nd June cancel with a Port-au-Prince coffee cancel of the 12^th of June right over it.

Puerto Rico

San Juan: The home of a lot of Roessler covers, including the infamous “Via Parachute” ones (see note below). The only cancel I've seen until now, was a Chapman cover (non-Roessler) that has a San Juan General Delivery on the back:

Note: For more details and information about the covers to each destination, link to the full article.