Contradictions in the Hobbit

[dancing spawn of ungoliant]

(I did the search but couldn't find a similar thread...)

I'm re-reading the Hobbit (again) and some things just don't seem to fit in when compared it to LotR trilogy and the way things are described there. Or is it because the Hobbit is written like storybook and not like some historic epic?

For example it is said about the Mirkwood elves that the only living creatures they didn't show any mercy were the giant spiders. There isn't said anything about orcs (or goblins if you like) and I can't see elves being too merciful to them either. Or does "the only" mean "the only plus then some other things"?

I have still a few examples left but have you noticed weird things or thing that doesn't really fit in the M-E you have learnt to know?