The blood stains Lisbon creates on Jane's gown change between takes and the ones on his sleeves disappear completely.
At 32:39 after the fake operation the left arm drops out from under the sheet to show the tattoo. The next scene the arm is securely tied under the sheet.
The FBI knew that Anthony Tremel had a Tattoo. They could never have the slightest idea how the tattoo was styled or written. Lark only told about the tattoo, but not about how it was specifically written on the arm.