Missing Countries & Territories

Asia：

Yemen

North America：

Dominica

Africa: 

Central African Republic 
Comoros
Equatorial Guinea
Guinea-Bissau
Somalia
Western Sahara

Oceania: 
Marshall Islands

Territories:

British Indian Ocean Territory (UK)

Saint Helena (UK) 

Ascension (UK)
Saint Martin (French)
American Samoa (USA)
Guam (USA)
U.S. Minor Outlying Islands (USA)
Bonaire, Saint Eustatius and Saba (Netherlands)
Tokelau (New Zealand)