An eagle-eyed fan on Reddit spotted an incredibly sly Batman Easter egg in Spider-Man: Homecoming.

Spider-Man: Homecoming invited a lot of jokes when it cast Michael Keaton as the Vulture. The actor famously played the Caped Crusader in the Tim Burton films Batman and Batman Returns. For a lot of fans, it was an added bonus to see Batman beat up on Spider-Man -- and that was clearly something the creators were fully aware of, if this Easter egg from the film is anything to go by.

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Reddit user deathstrokejt posted to the Marvel Studios subreddit with a freeze frame from the first confrontation between Spider-Man and Vulture. At one point, Vulture is framed against the moon. Doing so quietly recreates one of the most famous pieces of the Batman lore: the Bat-Signal.

It’s just the latest Easter egg to be found in the MCU films. This series of movies has been going on so long that a lot of small character moments are actually callbacks. That’s alongside a whole host of other deep cuts and shout-outs to the comics lore -- and apparently not just to Marvel characters.

Jon Watts' Spider-Man: Homecoming sequel Far From Home stars Tom Holland as Peter Parker, the friendly neighborhood Spider-Man. It is scheduled to be released on July 5, 2019.