Hey, I dug into this because titles like '99 Days' pop up in different places and confuse people a lot. There isn’t a single universal cast I can rattle off without pinning down which production you mean — there are movies, shorts, and even regional films and series that use the same name. What I usually do first is find the release year or the country of origin: that immediately tells you whether you’re looking at an indie festival film, a Bollywood/Indian regional project, or something from Europe or Nollywood.
Once I have the right entry, the cast credits become obvious: top-billed leads in the opening credits, then supporting cast and cameos in the full IMDb/Wikipedia listing. For example, trailers and festival program notes will flag the lead actors, the IMDb page shows the full cast and character names, and press kits list featured guest stars. I like checking a film’s distributor or streaming page too because they often show the main cast under the synopsis. Personally, I always enjoy comparing the official cast list with who actually appears on-screen — there are fun surprises when a “supporting” role steals scenes.