Data exported out of the Fulcrum OpenTrails Trailhead App requires some post processing in order to generate the proper files, per the OpenTrails trailheads.geojson specification. Simply export as Shapefile and execute the following GDAL/OGR commands:
ogr2ogr -f "SQLite" opentrails-trailheads.sqlite -nln "trailheads" -a_srs "EPSG:4326" opentrails_trailheads.shp
ogr2ogr -update -f "SQLite" opentrails-trailheads.sqlite -nln "osm_tags" opentrails_trailheads_osm_tags.dbf