Another one that is frequently brought up is 「ご注文は以上でよろしかったでしょうか？」, where the "correct" form is 「ご注文は以上でよろしいでしょうか？」.

Adding 「～のほう」 is also very common (e.g. 「お車のほうは大丈夫でしたか？」).

These are all attempts to soften the language (i.e. to be more polite) (at least according to my theory!). The first example uses past tense, the second uses an indirection by talking about the "direction where the car is" rather than just directly mentioning the car itself.

IMO it's always tough to define what is "incorrect" and "correct". After all, even when you look at the Japanese language just 30 years ago, it's quite different from how it's spoken now. Not to mention how it changed since the Meiji-era etc. :p

Personally I find these indirections annoying but perhaps that's just how the language is evolving. Right now though, it is true that many consider these 敬語 to be wrong. Especially older ppl.