Macau Cantonese, any differences from HK?
A quick browse on Google Scholar yields a few results. Macau Cantonese appears to be intermediate between Zhongshan Cantonese and Hong Kong Cantonese.


There is only one rising tone derived from Middle Chinese 上聲, which is pronounced closer to the lower one of Guangzhou and Hong Kong Cantonese. This brings it closer to Zhongshan Cantonese.
However, this high rising tone re-appears in changed tone even in the Macau version of Cantonese, so the number of contrastive tones remains 6.
There is no longer the distinction between the high falling and high level tones, much like Hong Kong Cantonese but different from Guangzhou Cantonese.
Similar to across the Yuehai region, /l/ is replacing /n/ as an initial.
There is the loss of the w-glide after k- and g- and before -o-, like Hong Kong, although that is meant to have started very early. It is already complete in Zhongshan-Shiyi.
This paper (in Chinese) points to a difference in the long monophthongs between Macau, Hong Kong and Guangzhou. But there's little indication of how the non-cardinal vowels are different betwee the three.


There is meant to be a few sentence-final particles which are particularly well-used in Macau:


The sentence-final particle mo4 is stated as being "rarely attested in Hong Kong Cantonese..." but "fairly common in Macau Cantonese, especially among older speakers", and is described as a less intense version of 咩 me1.
I can't access this 2013 paper, but it seems to deal specifically with Macau Cantonese's particles.


Finally this 2010 review summarises research on Macao's evolving linguistic situation. It does mention something about the slight influence of Portuguese in loanwords, and the difference in the way English loanwords are employed in Macao vs HK media.