The "tell" that I'm primarily relying upon is that you often drop articles where a US-native speaker would use them. Just one example: https://news.ycombinator.com/item?id=13197570 (that was as far back as I went) I think most native US speakers would use "the gun industry" and "the film industry". Several later comments drop an "an" or "a" article as well.

You also have a habit of using a comma splice rather than a semi-colon to join sentences, but that one is harder to place geographically, as it's a somewhat common trait within the US as well. In my experience, it is often a trait of European native speakers who learned English as a second language, but is less reliable than dropped articles.