Meet Daniel Radcliffe, Professional Dogwalker

Last summer, images surfaced of Daniel Radcliffe leashed to a horde of dogs in New York City's Bryant Park. The gossip mill hypothesized a cameo role in Amy Schumer's upcoming flick Trainwreck , though the film's director Judd Apatow quashed the rumors on Twitter with the response, "Not true! He was just walking his dogs." The rumors were true, though; Radcliffe's IMDb page was updated just hours later to reflect his work in the movie. Now that the film is out, I can confirm that he makes an appearance as a dog walker in the eponymous short The Dogwalker that Schumer's character watches with boyfriend John Cena. It's a brief role as a lovestruck dog walker romancing a dog owner played by Marisa Tomei, making quite a heavy-hitting pair for a bit part. Radcliffe plays the leading man of what Schumer envisioned as the "worst movie," according to a June question-and-answer session with Glamour.

In the same interview, Schumer revealed that Radcliffe, surprisingly, wasn't her first choice for the part. It turns out that she had written the role with Joaquin Phoenix in mind, though she wasn't sure he ever got the memo. (I'm sure that if he had, he would have jumped on board — earlier this year, the actor told Jimmy Kimmel that he has quite the crush on Schumer.) Instead, producers suggested Radcliffe for the role and Schumer welcomed the suggestion.

Radcliffe reportedly leaped into the role, which was entirely improvised (unfortunately, little dialogue is actually heard). His contribution to the scene, the now-iconic dog-walking belt he sports, was inspired by a man he saw walking down the West Side Highway in Manhattan, the actor told Seth Meyers. Though his appearance is brief, it's a memorable meta-scene within Trainwreck. Films within films appear as a frequent motif to add layers to the main narrative (here, spoofing the romantic comedy form within Schumer's more acerbic romcom). The best pull at the edges of the movie's commentary, stretching them within the confines of the film to drive home a point or provide a counterpoint. Here are a few of the finest movies-within-a-movie, because Trainwreck almost certainly leaves you wanting more.

1. Birdman Returns, from Birdman (2014)

"In a time of darkness, in a world of chaos..." opens the dreary, dismal trailer for Birdman Returns, Riggan Thompson's sophomore effort for the Birdman franchise in the film of the same name. Birdman is a meditation on the cult of celebrity and the costs of the public persona for the private individual. Birdman himself — an overblown, husky-voiced, absurdly costumed action hero — hyperbolizes the action franchise industry, but it's only with aid from moments like this trailer that the film really achieves the meta-commentary it strives for.

2. Angels Live in My Town, from Boogie Nights (1997)

Clocking in at just under a minute, the trailer for Angels Live in My Town finds Mark Wahlberg and John C. Reilly bumbling through an action-porno. Its amateur aesthetic drenches this love-letter to the porn industry. The Dissolve aptly described it: "It might not be great art, but it’s ambitious bad art."

3. Stolz der Nation, from Inglourious Basterds (2009)

Eli Roth, who also stars in Inglourious Basterds, directed this set-piece for the climax of the main film. The title translates to Nation's Pride, and it screens at Mélanie Laurent's movie theater for Hitler and the Nazi leadership. As a German sniper cornered in a crow's nest takes on a hefty portion of the United States's Army, so the German audience itself is trapped, to be picked off by the Basterds in a fiery conclusion. It provides a counterpoint for Tarantino's plot while spoofing German propaganda films.

4. Stab, from Scream 2 (1997)

As Scream accumulates more and more sequels, so does its meta-film-franchise Stab, which is based on the events of Scream itself. At last count, the Stab series had six installments — even more than Scream, which released the fourth film in 2011.

5. Tropic Thunder

I'd be hard-pressed to select a favorite meta-film moment from Tropic Thunder, since the whole film recounts the ill-fated production of a Vietnam War epic. The actors — Jack Black, Robert Downey, Jr., and Ben Stiller, to name a few — are dropped in the middle of a jungle rigged with guerrilla explosives both live and blank. But if forced to choose, perhaps the most memorable instance of film-within-a-film is the series of fake trailers that accompany Tropic Thunder, which convey the film's teasing ambiance and plays on genre tropes from romance to comedy to action.

6. Angels With Filthy Souls, from Home Alone (1990)

To avoid paying for a pizza, Kevin McCallister (Macaulay Culkin) plays a scene from the gangster film Angels With Filthy Souls hoping to scare away the delivery man. Angels With Filthy Souls parodies a 1938 gangster film entitled Angels With Dirty Faces — though the original film might not be quite so scare-worthy, I'd be interested in a film that would earn free delivery. Home Alone 2 also contains the sequel, Angels With Even Filthier Souls.

The movie-within-a-movie motif often plays on genre conventions. Tropes already implemented — or called into question — in the primary narrative are reflected yet again, stretching assumptions and audience expectations in an exciting and often hilarious way. (And honestly, for many of them, I'd like to see feature-length adaptations — The Dogwalker included!)