This goes under the heading of trivia question theology. It was discussed in a Facebook group that I am part of. My answer is that when Jesus appears in the upper room to his Apostles, and later to Thomas in particular, he has been resurrected and appears in his glorified body. He can do things like appear and disappear in rooms with all the doors and windows closed. He instantly disappeared from their sight once the men on the road to Emmaus recognized who he was. He showed Thomas the nail prints in his hands and let him feel the wound in his side. Why would Jesus have these wounds after his resurrection? While I believe that there will be no sickness or death in heaven, and that we will be healed of all infirmities, our identity is hid in Christ and his redemptive work is very much tied tied to his death on the cross. Calvary is the point where heaven touches earth. His wounds may be visible for this reason; they are a major part of his story. Those marks define the crucified savior, the suffering servant of Isaiah 53. My reasoning for the wounds being visible may be speculative but the fact that we see Jesus with them after the resurrection is firmly based on the Gospel accounts.