Yeah, for US money the serial number is prefixed with a letter to donate the year it’s from and the note also has a series year for the actual design printed on it.
Money has evolved a lot since the 1980s so modern money would be obvious. And banks in the 80s would probably be pretty hot on money fraud as hard case was so central to the economy.
A better option would be to collect money printed prior to the year you wanted to time travel to. It’s unlikely they would be able to detect duplicates of real money already in circulation elsewhere in that time. But it might be hard to fine money that old in large volumes as so much gets taken out of circulation and replaced with new money every year.
You could also go to any point in time where you were already of the age of majority and purchase a large winning lottery ticket the drawing before our present history indicates that it won.
That would get you plenty of money and then being a rich lottery winner and purchasing a million dollars worth of Apple computer or something I would not be that particularly noteworthy.
Just go and spend the rest of the 10 or 12 million dollars that you have living conspicuously and wait out the 20 or 30 years until that initial million dollar investment makes you nearly a trillionaire.
