Currently the /post/:id/comments endpoint only returns a limited number of comments on a given post. There is no obvious way to fetch all of the comments on a post when a post has thousands of comments.
Suggestion: add pagination parameters to the endpoint to allow querying comments on a post in batches, i.e.
/post/:id/comments?page=N
Where page=N specifies querying the N-th page of the results for that given post