This is the map from 2024 DL Half. There's nothing in the 2025 Halloween Half guide about this. So I'll presume this should be close.
The 5k starts inside of
Disneyland Park on Main Street, so just walk there like normal, only in the dark.
This is for the 10k and half.
View attachment 999867
This is the parking lot east of Del Sol Inn and Grand Legacy at The Park. The south entry is on Disney Way, just past The Anaheim Hotel. Getting past security there will put you right in the corral area. The entrance to the northwest is accessible by going between Camelot Inn and Tropicana Inn. That will put you in the parking lot north of this, and then there will be a path from that lot into the race lot.