What is the earliest example of a 'gag reel'?

Back in the 30's and 40's, Warner Brothers used to produce a yearly "Breakdowns" film containing bloopers from films produced during the last year. They'd show the films during an annual dinner for the staff.

You can find a collection of these films on archive.org. The earliest one in their collection is Breakdowns of 1936. The films are in the public domain so they're also easy to find on Youtube.

Breakdowns of 1939 is somewhat well-known for having a sequence of Porky Pig "bloopers", contributed by the cartoon division--which was actually produced especially for the blooper reel, because the cartoon-making process at the time wouldn't produce bloopers.

This youtube video has the Youtube title "Breakdowns of 1935". The actual film has no title card or date. But the end card says it's from Warner, and it contains segments from Warner films from 1934-1935. It could be another gag reel from before they adopted the "Breakdowns" name.

Not an answer, just an 'interesting' anecdote. Please don't vote it either way, it's just a bit of background info.

Back in the 80's - before the days of YouTube or even "It'll be Alright on the Night" which was the first UK show to air out-takes and bloopers from recognised actors and broadcasters - the BBC's VT department used to edit together a gag reel from their own shows during the year. They would set it up like a single presenter show, probably using down-time in one of the news studios, and use a famous face from the time to actually do a quick & dirty presentation for it.

These were then broadcast internally around the various local BBC satellite stations around the country in the run-up to xmas, and either watched by groups of people at lunch-time in a spare room, or the canteen etc; or they could grab a copy on VHS to bring home to show their friends.

Because this was known and quite 'famous' inside the organisation, you would often see bloopers/gaffs made by actors or presenters who, once they realised how badly it had gone wrong, would often turn to camera with a sheepish grin and say "Merry Christmas, VT"

I thought I'd Google "Merry Christmas VT" to see what I could find - seems it even has its own Wikipedia entry these days - Christmas tape

BBC4 even made a show about it - The Secret Story of the BBC Christmas Tapes. The show itself is no longer available on there to watch, but there's a long write up about it.

A quick trip round YouTube brought me this list - many of the BBC and other networks' xmas tapes. Note: bad language is likely to be unexpurgated, these were never designed to be seen by the public.

Star Trek conventions often showed blooper reels or gag reels from Star Trek: The Original Series back in the 1980s and probably even the 1970s.

As I remember there were separate blooper reels for the first, second, and third seasons. Thus it is possible that they were compiled at the end of each season, and thus in 1967, 1968, and 1969.

So if that dating is correct any earliest American television blooper reels would have to be made before the Star Trek blooper reels and/or shown to the public before the Star Trek ones were first shown at conventions in the 1980s or 1970s.

In 1937, the Hal Roach Studio cut together scenes from various Laurel & Hardy films as well as bloopers of actors swearing into a short called That's That. It was a gag reel for Stan Laurel's birthday. It will be included on the Laurel & Hardy BluRay collection that will be released in June, 2020.