It was a joke. Shane told you upfront, and you still got fooled. Watch for the question, "How did you know it was a joke?" The technician looks to Aaron, who in turn gives a slight shake. No answer, not in front of Aaron. Blame Abe. He fell for the red herring, therefor everyone else did. Originally, Aaron may have put the fungus there as a joke. True, the original time line #2 has been replaced and the first play of it can not be truly known. This joke led to Abe discovering that actual time travel was occurring. Or so Aaron(1) thought. The truth is, Abe discovered this somehow, built two boxes, and Aaron came out without Abe's knowledge. Very likely, Abe may not have even finished the second box yet. As soon as the first box is working and turned on, someone will exit. After Aaron finds out that the box is actually time travel, what should he do when he exits the box before Abe has used the box for his first day trip? In imitation of the original time line and in order to insure against any paradox, Aaron(2) purchases the fungus, place it on the Weeble, and allow a replay of the day Abe approaches Aaron on the park bench. Since only the last revision counts, the lab tech will only experience Aaron(2) acquiring the fungus. (At least for now, until we discuss Aaron(3).
How did this not prevent Abe from climbing in the box? It should have left Aaron in complete control. However, if Aaron skips this event in a rewrite, could he jeopardize his own existence? Why didn't he exit and sabotage Abe's box? Pure greed and power, right?
Granted, in an earlier concept, Aaron(1) could be clueless. The technician would not know that there is an Aaron(1) and Aaron(2). Thus, in front of Aaron, the technician does not give an answer to Abe’s question. In the original time line, Aaron(1) may have planted the fungus as "a joke." Then,Aaron(2) could plant the fungus which would make Aaron(1) innocent, surprised, and clueless.Later, Aaron(2) may repeat the same process of planting the fungus (that is if he drugs Aaron(1) in that particular time line). This may keep a constant feature in the new time line.
So Abe’s first reaction was correct, "What did you do to this thing?" Part of the proof that we are watching Aaron(2) or Aaron(3) is the joke that Aaron starts to tell in his office. Thus, proof of the time loop, whether Aaron repeats this joke from memory or a recording (in the time line, he hasn’t heard it yet). There can be no debate though, Abe is definitely talking to an Aaron who has traveled back in time.
What does it accomplish? It insures that Abe will build and store his boxes in the U-Haul storage center, a climate-controlled environment. It is certainly safer out of town so that no one may see them and their doubles. This step is essential to their success. It may also be an attempt to convince Abe not to get in the box (from Aaron’s perspective). This would allow Aaron sole control over the boxes. It is easy to believe that Aaron hasn’t traveled in time yet, because Abe is still under that belief. It is very hard for many people to grasp on their first viewing, even after reading the explanation. But, Abe built a box early on. Long before most fans realize it, even after several viewings.
