Commodore had 3 capacitors mounted backwards on the A3640, the CPU board of the Amiga 4000 with 68040 processors: https://youtu.be/zhUpcBpJUzg?si=j6UFmIJzoC-UDS6u&t=945
Also mentioned here: https://amiga.resource.cx/exp/a3640
ZX Spectrum +2 shipped with transistors backwards: https://www.bitwrangler.uk/2022/07/23/zx-spectrum-2-video-fi... This even caused visible artifacts on the display, which was apparently not enough for the problem to be noticed at the factory.
I think Clive Sinclair was notorious for wanting products to be brought to market quickly, with pretty aggressive feature sets. They very well may have noticed it at the factory, but didn't want to do a fix because it was technically functional.
Commodore just kept doing this. Just listing shoddy craftsmanship would take forever, and then we get to intentional bad decisions, like giving the A1200 a power supply that's both defective (capacitors ofc) and barely enough to support the basic configuration with no expansions, which is extra funny because PSUs used with weaker models (A500) had greater output...
This was the hardware patch I had to install to use a CyberstormPPC: https://powerup.amigaworld.de/index.php?lang=en&page=29
The number of used a500 power supplies I sold to customers when I upgraded their a1200 with a GVP 030 board + RAM...
Classic Commodore Quality :P
They also had backwards caps on the CD32 and A4000