Great to see another PICO-8 game! It might be a small thing but I'm really in awe of the physics of the connecting lines, practically behaves just like real string! Also you're probably aware but there's a tiny bug where the falling cards turn invisible. Not sure of the trigger but it was around when I was rushing it towards one side of the screen.
Viewing post in MURDER TETRIS jam comments
I tried a couple more times, it only appeared once again and seemingly late game. It would happen as the card was falling, around the 2nd row from the top on the first column on the left. I believe in this case it was a light blue card and it just completely melded with the background colour. In the bug I experienced before, the card was still "there" and cards could stack on top of the invisible card. Perhaps it's to do with pal()? If that's the way you're producing all these colour cards.