Is I looked at the sea of yellow faces a metaphor?

No

Explanation:

In his use of the phrase, "sea of yellow faces", the narrator firmly establishes himself in contrast to the local Burmese villagers.

awnser:

one thing blogging and good copywriting share is a conversational style, and that means it’s fine to fracture the occasional rule of proper grammar in order to communicate effectively. both bloggers and copywriters routinely end sentences with prepositions, dangle a modifier in a purely technical sense, or make liberal use of the ellipsis when an em dash is the correct choice-all in order to write in the way people actually speak. but there are other mistakes that can detract from your credibility. while we all hope what we have to say is more important than some silly grammatical error, the truth is some people will not subscribe or link to your blog if you make dumb mistakes when you write, and buying from you will be out of the question.