 CONT: Early on, when David Banner sneaks into Dr. Pratts lab, he  erases a letter from work board showing the scientific equation of  DNA structure and substitutes the letter "A" for what he has erased.  At various times during the movie, when the board is shown again,  the letter "A" is in different handwriting (one must look closely to  see). Sometimes the top of the letter is rounded off, sometimes it  comes to a sharp point. Sometimes the two "legs" of the letter "A"  are equal, sometimes the right "leg" is longer than the left "leg".