This 1990 Philadelphia hundred has the imbedded security on the wrong side. Not a dramatic error visually, as it is best seen by holding the note up to the light. But a very significant error nonetheless. This example is a PMG Extremely Fine-40. This error note type, unlike most others, is virtually unseen in CU.

In 1990, the Treasury introduced new security features to the $100 note, chiefly the microprinting around the portrait oval and the imbedded plastic strip. A small number of these error notes were created when the sheets were inserted upside down during the first printing pass. The 1990 & 1993 Series are the only one where this error is possible in this design as the "Big Head" notes were introduced in the next Series.