You may have seen them before. From that “How to Draw Manga” I came across in a London museum (above tweet, possibly by an American author), to having the “の” (or its romanised form “no”) being used excessively like “Ookami no Jutsu” or, if in Chinese, something like “时间の乐趣”.
If you aren’t familiar with Chinese or Japanese, notice the random の being used as a substitute for 的 in the middle of a Chinese sentence that contains characters that aren’t normally used in Japanese, or used only in Simplified Chinese. If you are having trouble telling apart a genuine Japanese product with a copycat from China (Taiwan especially), look at the design like the fonts used: some products uses particular fonts that are commonly used on other Japanese products, but never elsewhere. If there’s a barcode, the first two digits of a genuine Japanese product should start with “42”. If it doesn’t, it’s not a real Japanese product.
Then there are overused Japanese themes used in the media that, while not historically inaccurate, it may give the impression to those who know nothing about Japan that it’s still filled with ninjas, samurai, geisha, houses are made up of low-rise wooden houses, and people get around by horses. To make things more complicated, there are actual dramas on Japanese TV that does look like it takes place in the Edo era (Early 17th century to mid 19th century) or earlier, which, if it is the only thing that a non-Japanese that knows little of the country were to see it would think that it is the modern-day Japan. (It’s possible if the influence is none or not obvious, and the local media hardly or doesn’t cover it at all, which itself you don’t watch.)
Until seemingly recently, I have also seen people using random katakana (or some typeface that tries to look like it) or some funny curved lines (which is also used in Chinese context) that are like what I call “chicken markings”. They then try to excessively use it when talking about Japanese things. Sometimes with some strange accent that even Japanese speaking English would never use. I said “until seemingly recently” because I almost never see them these days. Possibly due to increased awareness of the Japanese language and culture, mostly through anime.