One of my pet peeves when I see pictures of kimonos originating in the west is "hidari mae", or wearing the kimono with the right side lapped over the left. Kimono are always worn with the left collar lapped over the right, except on a corpse. The term "hidari mae" is also a colloquial expression meaning ebbing fortune or people facing bankruptcy. So it is very unlucky to wear your kimono "hidari mae", and certainly would give a Japanese person a sense of discomfort to see it!
The custom originated in the Nara period in the seventh century, when the Japanese court began to follow the Chinese fashion. For a while there was some confusion with people wearing their collars the old-fashioned way, or the Chinese way. Emperor Gensho (715-724) eventually unified the system of measures, and brought about many regulations, one of which was to conventionalize the method of dress - and from that time Japanese people wear their kimono left side over right.
This isn't a mistake a native Japanese person would make, but with the popularity of Japanese art and culture, many artists (including myself, occasionally) make the mistake and draw the collars incorrectly. There are a lot of people who enjoy dressing in kimono as a hobby, and often get this little detail wrong. I've seen it so many times, and every time it's just as jarring to my eyes.
A couple of examples:
This first from a fabric company. I've noticed that a lot of ukiyoe inspired fabric is offen drawn incorrectly. Actually, this first example is very cute, but barely recognizable as Japanese.
Second, from a book cover. Yes, I've read this book, but I wouldn't recommend it.
I've noticed the same thing with kanji, because often westerners can't tell which way the kanji should be, and seem to abitrarily flip their photots and post them any which way!