The loss of *h in all non-initial positions seems to be a distinctive North Germanic feature:
(before a consonant) Icelandic nótt "night" vs. Old English niht / neaht
(word-final) Icelandic sá "(I/he) saw" vs. OE seah
(medial) Icelandic tíu "ten" vs. Gothic taihun
This change has occurred in modern English, but it did not occur generally in the branch of Germanic that English comes from (as the Old English forms above show).
Another such feature is the mediopassive verb form: e.g., Icelandic sjá "to see" vs. sjást "to be seen, to see oneself, etc.". As far as I know, the mediopassive suffix -s(t) is only found in North Germanic.