use /global/ sugar for bare globals, no leading /

code/modules/overmap/ships/engines/engine.dm

@@ -1,6 +1,6 @@
 //Engine component object
 
-var/list/ship_engines = list()
+var/global/list/ship_engines = list()
 /datum/ship_engine
 	var/name = "ship engine"
 	var/obj/machinery/holder	//actual engine object

code/modules/overmap/turfs.dm

@@ -87,7 +87,7 @@ var/global/list/map_sectors = list()
 		GLOB.overmap_event_handler.on_turf_exited(src, O, newloc)
 
 //list used to track which zlevels are being 'moved' by the proc below
-var/list/moving_levels = list()
+var/global/list/moving_levels = list()
 //Proc to 'move' stars in spess
 //yes it looks ugly, but it should only fire when state actually change.
 //null direction stops movement