Are there any common grammatical errors made by native Japanese speakers?


Sorry if this is a really open-ended question, but one thing occurred to me
when I was asking a prior question here; are there any particular grammatical
errors frequently made by _native_ Japanese speakers?

For example, in English there are quite a few obvious mistakes that native
speakers make - `your` vs. `you're` and `me and Sally went...` rather than
`Sally and I went...` and often non-native speakers of English are better at
distinguishing between them than native speakers.

Is there any such Japanese grammar that is commonly used incorrectly by native
speakers?

I am more interested in common mistakes than obscure mistakes; mistakes where
one would think that a native speaker should know better.




If some construct is common among native speakers, is it a grammatical error,
or an artifact of a shared dialect? It's an error in the prescriptive sense,
in that it is contrary to some preferred dialect that is promulgated by
schools and institutions.

Here is an example: using 全然 (zen zen, _[not] at all_ ), in the positive sense
( _totally_ ).

"昨日, 全然楽しかったよ！” (Kinou, zen zen tanoshikatta, yo! _Yesterday was totally fun!_
)

