A short stretch of ERR RoW still exists in Eliot, on the NE side of ME 236 at Wooster Rd. The highway builders bypassed a fairly deep cut. In the early 1960s, several driveways which probably had originally connected to ME 103 still had wood bridges over the cut. You could still see some of the rock walls of the cut last time I passed through, but it's been a convenient place to dump stuff for almost 70 years.
Spinney's Switch (about MP B60.5) was the RR West end of a stretch of double track whose East end was Jewett. This was removed before 1939, possibly at the same time as the ERR was single tracked from Newburyport to Emery.
Day's Siding ran between approximately MP B89.3 and B89.6 on the inland side of the main track and had a shorter siding next to it. The old track chart image I'm using shows several culverts and one private road, but no other detail.