Movies are now generally packed to the brim with Easter eggs, references and fun nods to other movies, other forms of media and people.
The movies in the hugely popular comic book genre are no different - in fact, such fun inclusions are more prominent in comic book movies than pretty much any other genre you can name - and that means directors get the chance to have a little fun and even, on occasions, give nods to themselves.
This has happened a number of times, whereby comic book offerings have including Easter eggs and nods that refer to projects the directors of said films have worked on in the past - it's vanity in its absolute most shameless form.
In this article, we're going to run through ten such instances from blockbuster movies in the comic book genre (which, remember, has been one of the most prominent genres in Hollywood in recent years and is still going strong). Here are ten nods directors gave to their previous work in comic book movies.
11 300 (Watchmen)
Zack Snyder's very underrated 2009 Watchmen movie is jam-packed with a number of nods to another of his comic book movies - 2007's brilliant 300.
In one scene, the door to the Comedian's room had the number 3001 on it, until some flying debris knocked the "1" off to leave it showing 300. There is another scene in which the combination to a psychiatrist's briefcase is 3-0-0. And, on some television screens in front of Ozymandias in his base, one of the sets is showing the original 1962 depiction of the Battle of Thermopylae, The 300 Spartans (interestingly, in one of the trailers for 300 - which came two years before Watchmen, remember - Rorschach from Watchmen could be seen for a split second in a single frame, foreshadowing the movie Snyder would go on to direct a couple of years later).
10 Slither (Guardians Of The Galaxy)
Guardians of the Galaxy had one particular scene that was a dream for any Easter egg-loving director. The Collector's museum scene enabled James Gunn to put an abundance of Marvel comic book species and artifacts on display - including the likes of Howard the Duck, Cosmo the Spacedog and a Dark Elf - but it also let him include some exhibits from other universes aside from Marvel.
Gunn grabbed the opportunity with both hands and opted to display some of the extraterrestrial slugs that were the antagonists (so to speak) of his cult 2006 science fiction horror movie Slither. Guardians of the Galaxy also included a cameo from Nathan Fillion, who starred in Slither and is a good friend of Gunn's.
9 Xena: Warrior Princess (Spider-Man)
Sam Raimi has had a highly impressive career in movies and television as a director, producer, actor and writer - and one of his many producing credits was the television show Xena: Warrior Princess, which he worked on numerous times during its original run between 1995 and 2001.
In the first movie of his Spider-Man trilogy - 2002's Spider-Man - he directed a nod towards his work on that show by giving a cameo to its star, Lucy Lawless. She's only on screen for all of about three seconds and comments on the emergence of Spider-Man by saying "a guy with eight hands... sounds hot" (which is, of course, wrong - but it's funny nonetheless).
8 The Nightmare Before Christmas (Batman Forever)
This is cheating somewhat, as Tim Burton had actually moved to the producer's chair by the time 1995's Batman Forever was released - with Joel Schumacher having taken over Bat-directorial duties - but you have to imagine that Burton would have been in on it, given his involvement in the movie.
There was a nod to Burton's The Nightmare Before Christmas - the brilliant and classic 1993 stop motion movie - in the form of a group of trick-or-treaters, one of whom was wearing a pumpkin mask reminiscent of the head of the movie's lead character, the king of Halloween Town known as Jack Skellington.
7 The Evil Dead (The Spider-Man Trilogy)
Sam Raimi again and this time it's a number of nods back to what is arguably his most famous work - the Evil Dead series of movies and, in particular, their lead character, Ash Williams. Ash was played by Bruce Campbell and Raimi recruited the actor for three separate roles in his three Spider-Man movies.
In 2002's Spider-Man, Campbell played the ring announcer at Peter Parker's wrestling match. In 2004's Spider-Man 2, he played the snooty usher who wouldn't let Parker into Mary Jane's play. And in 2007's Spider-Man 3, he played the maître d' at the restaurant in which Parker intended to propose to Mary Jane (Raimi's children also appeared on screen during the final battle in Spider-Man 3, which is kind of a nod to his past "work" as well!).
6 Batman Begins (The Dark Knight Rises)
This might seem like an odd one, because of course there are going to be references to previous movies in the same trilogy, but this particular nod to 2005's Batman Begins in 2012's The Dark Knight Rises is particularly clever and one that director Christopher Nolan clearly went above and beyond to include.
In Batman Begins, there is a scene in which the young Bruce Wayne is shown a necklace that is intended to be a gift for his mother. In the trailer for The Dark Knight Rises, Anne Hathaway's Selina Kyle AKA Catwoman is seen putting on a necklace whilst looking in a mirror - it is clearly meant to be that same necklace from Batman Begins, suggesting that she has stolen it somewhere along the line and showing how far ahead Nolan was thinking - even when it came to Easter eggs - back when he was working on the first movie of the trilogy.
5 Swingers (Iron Man 2)
Jon Favreau directed both of the first Iron Man movies and in 2010's Iron Man 2 he opted to include a very fun nod to a movie he had directed in the past - 1996's Swingers.
During the Stark Expo event in the movie, in which Sam Rockwell's brilliant antagonist Justin Hammer is due to present his Hammer Drones to an enthusiastic audience, Hammer gets a little bit cocky during his entrance and busts out a cheeky little trademark dance. Credit where it's due, he's got the moves, but the key aspect of this scene as far as this article is concerned is that he is dancing to the tune of Average White Band's Pick Up The Pieces - a record that is famously on the soundtrack of the aforementioned Swingers movie.
4 Kiss Kiss Bang Bang (Iron Man 3)
Kiss Kiss Bang Bang was a 2005 neo-noir black comedy crime movie directed by Shane Black and starring Robert Downey, Jr. So, when the pair reunited for 2013's Iron Man 3, it was only fitting that Black would throw in a number of nods to their previous work together.
Amongst the Kiss Kiss Bang Bang references includes an unreliable narrator giving up on trying to recite a famous quote (which Kiss Kiss Bang Bang also had), a Christmas scene (all of Black's movies tend to have one, not just Kiss Kiss Bang Bang), a broken finger (Downey, Jr.'s character lost a finger in Kiss Kiss Bang Bang, while Harley breaks a finger off the Iron Man armour in Iron Man 3), the term “the Hispanic Scott Baio” (it's a variation of a game Downey, Jr.'s character plays with Michelle Monaghan in Kiss Kiss Bang Bang, describing people as foreign versions of actors), Tony Stark abandoning Harley in his car (Downey, Jr.'s character was abandoned by Val Kilmer in the same way in Kiss Kiss Bang Bang) and the voice-over at the end starts in almost exactly the same way as the closing monologue in Kiss Kiss Bang Bang (and there are others).
2 Watchmen (Man Of Steel)
Zack Snyder again - and this time he's referencing the film in which he previously referenced 300! That film is the aforementioned Watchmen and Snyder included a sneaky nod to it in his 2013 Superman offering, Man of Steel.
During the epic climatic battle between Henry Cavill's Superman and Michael Shannon's General Zod, at around the point that Zod picks up and hurls a tanker truck, you can clearly see that the motif associated with the Watchmen comic books - a yellow smiley face with a drop of blood coming from it - is behind the Man of Steel on a wall as graffiti.
1 The Buffyverse (Avengers: Age Of Ultron)
In Avengers: Age of Ultron, during the scene in which Thor has his mind manipulated by Scarlet Witch, the Asgardian has an experience that takes him back to his home realm. In the vision, he converses with Heimdall, who warns him of a coming threat (Thor: Ragnarok) and, in the background, wolf, ram and hart masks can be seen, which is a nod to Wolfram and Hart - the evil law firm in Whedon's television show Angel.
Whedon also brought along his regular collaborator Alexis Denisof for the first Avengers movie, in which the man who played Wesley Wyndam-Pryce in Buffy the Vampire Slayer and Angel portrayed Thanos and Loki's ally, the Other.