The four that bite.
In the order they usually cost somebody money. The first two are about how a number or a date is written down; the second two are about what the file means by a name and by a unit.
The date could be two different days
03/04/2026 is 3 April in most of the world and 4 March in the United States. Both readings are valid dates, so nothing downstream can detect the mistake. Read the wrong way, every date up to the 12th of a month is wrong and the import still reports success. China, Japan, Korea and Taiwan write the year first, which is a third reading again. The only reliable signal is a day above 12 appearing somewhere in the file, which proves the order outright.
The decimal point might be a comma
Most of Europe and Latin America write 1.234,56 where the Anglosphere writes 1,234.56. Read the wrong way round, an amount comes out a hundred times too large without producing anything that looks like an error: 1234,56 becomes 123,456.00, and that is a perfectly well-formed number. India adds a third convention, grouping in lakhs, so 1,00,000 is one hundred thousand and not one hundred.
The merchant name is not the merchant
The name on a card transaction is a billing descriptor, usually capped around 22 to 25 characters. What arrives is often the payment processor rather than the shop, or the group that owns the brand rather than the brand, or the company on the incorporation papers rather than the name above the door. Whichever it is, it has usually been truncated on the way.
Not every currency has two decimal places
The yen and the Korean won have none, so 1500 means 1500. Dinars in Bahrain, Jordan, Kuwait, Libya, Iraq, Oman and Tunisia have three, so 1.234 is one dinar and 234 fils. Anything that assumes two will either refuse a three-decimal amount or store a zero-decimal one a hundred times too large.