Database

db={actors:[{"name":"Pedrito"},{"name":"Chris Evans"},{"name":"Chris Hemsworth"},{"name":"Mark Ruffalo"},{"name":"Robert Downey Jr."},{"name":"Scarlett Johansson"},{"name":"Tom Hiddleston"},{"name":"Tom Holland"}],movies:[{"title":"The Avengers","year":2012,"cast":["Robert Downey Jr.","Chris Evans","Mark Ruffalo","Tom Hiddleston","Chris Hemsworth"]},{"title":"Thor: Ragnarok","year":2017,"cast":["Chris Hemsworth","Tom Hiddleston","Mark Ruffalo"]},{"title":"Captain America: Civil War","year":2016,"cast":["Scarlett Johansson","Tom Holland","Chris Evans","Robert Downey Jr."]},{"title":"Avengers: Age of Ultron","year":2015,"cast":["Scarlett Johansson","Robert Downey Jr.","Chris Evans","Chris Hemsworth","Mark Ruffalo"]},{"title":"Avengers: Infinity War","year":2018,"cast":["Robert Downey Jr.","Chris Hemsworth","Mark Ruffalo","Chris Evans","Scarlett Johansson","Tom Holland","Tom Hiddleston",]},{"title":"Iron Man 3","year":2013,"cast":["Robert Downey Jr.",]},{"title":"Spider-Man: Homecoming","year":2017,"cast":["Scarlett Johansson","Tom Holland","Robert Downey Jr."]},{"title":"Thor","year":2011,"cast":["Chris Hemsworth","Tom Hiddleston",]},{"title":"Thor: The Dark World","year":2013,"cast":["Chris Hemsworth","Tom Hiddleston"]}]}

Query

db.movies.aggregate([{$unwind:"$cast"},{$lookup:{from:"actors",localField:"cast",foreignField:"name",as:"actores"}},{$group:{_id:"$actores._id",actor:{$first:"$cast"},peliculas:{$push:{_id:"$_id",title:"$title"}}}},{$unwind:"$_id"}])

Result