Pointer arithmetic. Go has "pointers" but they're really more references. Some other things depend on how you look at them; Go "removes" manual memory management from the language by adding GC, it "removes" the fact that in C values are essentially untyped and very easy to penetrate down to that untyped layer by making all values carry their type around regardless, they "remove" the limitations on function pointers to provide real closures, they "remove" trivial array overflow by adding checked access, there's a lot of rough edges removed from C at the language level even if it required "adding" some runtime support.
I mean, by the time you've removed pointer arithmetic and manual memory management, you are by no stretch of the imagination in C anymore.
Given the fact that C is basically the blueprint for Go, I'm not sure what things were taken away from C, syntactically speaking. It's more like Go added garbage collection to C, and a few other bells and whistles and told people : "this is 21th century programming", without actually thinking about what C got wrong at first place.