So take "The Matrix", "The Office", Wallace and Gromit, a couple of B-grade Twilight Zone episodes, and add a very healthy dose of the classic Loony Tunes "Duck Amuck", mix them in a blender, and you will get something close to "An Ostrich Told Me the World is Fake..."
I will say from the outset that there were several laugh out loud moments here, as the existential crisis of an office worker who (no spoilers, it's in the title) has reason to believe he's not actually real develops. It's an enjoyable little piece of pulling back the curtain to see how the Wizard of Oz operates, with what I'd normally say is a fun and intriguing premise.
That's where this left me a bit flat (no aspersions on our more two-dimensionally oriented animators) however. The ground here, so well sowed by PK Dick, has been amply harvested in recent years by "Vanilla Sky", "Inception", and a host of others littered across streaming outlets. There's no big reveal here, as you know from the first moment what the character eventually learns. Then there's no release to the tension, as in the end everything is as the viewer sees it to be from frame 1 (I know this because the frames are all counted off in the corner of the screen - a shoutout to Godard's "Le Mepris", perhaps? At least among many other films-within-films premises.)
So we're left with a feeling of unease, sadness, and no real insights into the dilemma our little office drone has. It's a cute little film but needed just a touch more story to complete it.