Deliberate mistake: During the scenes where Maverick is flying the Darkstar spy plane, his helmet is lit up on the inside, so we can see his face. In reality the light would be reflecting off the plexiglass, meaning we would not be able to see his face, and he would not be able to see at all.
Deliberate mistake: At the end of the car chase with Penguin Batman's car drives upon a ramp at high speed before the explosions occur but his car only appears flying through the air and landing 15 seconds after the explosions. That's quite a long jump. (01:23:33)
Deliberate mistake: One of the first shots in Greece shows Benoit Blanc and Lionel standing on the pier. As director Rian Johnson himself says in an interview for the Vanity Fair Youtube channel, "Matches nothing else in the scene lighting-wise, but it's gorgeous soooo...who cares." (00:13:30)
Deliberate mistake: Considering the position of the surveillance camera (height and angle - almost parallel to the side of the building as well as to the sidewalk), plus the lens being indented within the outer frame, it would not have been able to capture a view of Redd on the sidewalk below like it did. (00:24:40)
Deliberate mistake: "Mama's Home Cooking" - a wood frame building in 1850 - was on fire in multiple spots (though not yet engulfed). The townsfolk lined up to pass a bucket of water to douse the flames, which would be futile given how involved the fires were, but they were able to extinguish the fires and the wood frame building was largely intact and the boards did not look charred. The building should have been smoldering hot for some time, but Angel was able to sift through the rubble to salvage some items. (01:45:58 - 01:46:56)
Deliberate mistake: There isn't an accurately-positioned light source bright or close enough that can project striped lines - especially that wide - across Rockit's face while he is lying in bed. (00:07:00)
Deliberate mistake: Except in certain angled views of Fred (with Matt in the passenger seat), the rearview mirror is darkened/blackened. (00:08:55)