Should I do anything when I see several references that are not used in the text?
There's nothing inherently wrong with this.  It's sometimes done to mention sources that provided general background information, or that the author suggests for further reading, but which weren't needed to support any specific claim within the paper.  Some journals don't allow this, but it's a matter of style. 

Even if the journal didn't want this, or if those references were included by mistake, it's a harmless error which just wastes a little bit of space.

If you have good reason to suspect that references were given in bad faith purely for padding, or to increase citation counts of other articles, then that would be misconduct - whether they were cited in text or not.  But otherwise I don't see that this represents anything improper, and there is nothing you should do about it.