Recently I was looking into Infrequent syllables of Cantonese that I found in the table provided by the Research Centre for Humanities Computing of the Chinese University of Hong Kong (CUHK) and the Unihan table provided by Unicode (see the combined table in Jyutping syllable table).

For some of this syllables I now found some more sources, that give information about syllable initials and finals. So instead of going through syllables I'll provide the information for syllable finals. The source used is:

Robert S. Bauer, Paul K. Benedikt: Modern Cantonese Phonology (摩登廣州話語音學). Walter de Gruyter, 1997, ISBN 3-11-014893-5. Google has a scanned version (preview).

• eu according to Bauer & Benedikt is pronounced /ɛw/,
• em is pronounced /ɛːm/,
• en is pronounced /ɛːn/, this syllable is not found in Unihan, the CUHK table includes it but gives no example,
• ep is pronounced /ɛːp/,
• et is pronounced /ɛːt/,

For all those finals no mapping is given to Cantonese Yale by this book. Furthermore the book 'Speak Cantonese' by Huang (Parker Po-fei Huang, Gerard P. Kok: Speak Cantonese (Book I). Revised Edition, Yale University, 1999, ISBN 0-88710-094-5) doesn't give any finals that could be mapped to those Jyutping finals.

There are still finals found partially in the CUHK and Unihan tables:

• um, found in the CUHK table without example, not in Unihan,
• up, found in the CUHK table without example, not in Unihan, too,
• oet, found in the CUHK table without example, though Unihan has character 㖀 for loet,
• oei, only found in Unihan with characters 唳, 捩 for loei,
• om, only found in Unihan with character 媕 for om,

These finals are not listed in Bauer & Benedikt so no IPA can be given.

Update: Cantonese: A Comprehensive Grammar (Stephen Matthews, Virginia Yip, Routledge, 1994, ISBN 0-415-08945-X) gives finals -em, -up, -et, -en, -um for Cantonese Yale (p. 20, chapter 1.3.1) and states that they are used in loan-words or as onomatopaeic sounds and gives examples lem, bup, wet, fen and bum.