Database
[{"resourcesInspected":["CD0626UHEA","CD0626UKE9"]},{"resourcesInspected":["CD0GNDPB1E"]},{"resourcesInspected":["CD0H7L789D","CD0H7L8RF7"]},{"resourcesInspected":["CD0FTHYK2B"]},{"resourcesInspected":["CD04H5K4B1","CD0725K788","CD0725K58A"]},{"resourcesInspected":["CD06JXHJ8A","CD04E9LCED"]}]
Query
db.collection.aggregate([{"$unwind":"$resourcesInspected"},{"$group":{"_id":null,"resourcesInspected":{"$addToSet":"$resourcesInspected"}}}])