History TheBigBangTheory / SeasonTen

* CelebrityParadox: A rather significant one, as Creator/ChristopherLloyd guest starred as a homeless man Sheldon recruits in a plan to get revenge on Leonard and Penny. Most of the time the big guest stars on the show are AsHimself with a bit of AdamWesting involved (more minor celebrities, especially those not from geek cred shows, get original roles), but here they had Doc Brown from ''Film/BackToTheFuture'' in their apartment and no one points out the similarity.

* {{Foreshadowing}}: Early into the season Howard is concerned that the Military's interest in their gyroscope project will result in them taking the project and leaving the guys with nothing. [spoiler: Come episode 23 and this is exactly what happened.]]

-->'''Col. Williams:''' You guys think you're the first government contractors to miss a deadline? We're still waiting on a giant space laser [[UsefulNotes/RonaldReagan Reagan]] ordered to beat the commies.

* RealityEnsues: In an effort to undercut an MIT team, Sheldon claims he, Howard and Leonard could miniaturize their gyroscope for the Air Force in 2 months. After desperately scrambling to find a way, they're finally forced to admit that it will take much longer. Their military contact just shrugs and accepts the new schedule.
-->'''Col. Williams:''' You guys think you're the first government contractors to miss a deadline? We're still waiting on a giant space laser [[UsefulNotes/RonaldReagan Reagan]] ordered to beat the commies.
** Two girls aren't really going to be interested in dating the same guy, as Raj found out the hard way.
** Someone with Sheldon's issues and personality quirks would be hard to live with. As a result, Amy struggled to have a good night's sleep and wanted to not do it anymore. One wonders how Leonard was able to do it for so long...
** Raj was careless with money because he was spoiled by his parents. As soon as he is cut off, his finances are so bad that he has to take odd jobs from Stuart and move in with Leonard and Penny.
** After spending an entire year working on their gyroscope, the guys are happy to have a finally working prototype. But when they show up the next day, they discover the lab cleaned out and Colonel Williams telling them that the military is moving on and they are not needed for the next stage. They protest but he makes it clear that the military only cared for the project, never for them.
** The guys spent months working on a gyroscope and got it down to the specifications agreed upon by them and the Air Force. Sheldon began some new equations that would reduce the current design by another 20%, but would be months of additional work and Leonard and Howard pushed him away. Col. Williams comes by to review the progress and catches Sheldon's preliminary math, and the promise of an even smaller design makes him want them to start over. It's far from the first time upper management decides on a change that sets back all the current development.

* MinorFlawMajorBreakup: While not a break-up, Penny and Leonard admit to the rest that they had a major fight over the holidays, one of the worst they ever had. It turned out they were watching ''Series/LukeCage'' together and Leonard found out she watched two episodes ahead of him. After thinking about it, they admitted that they were also strung out from a stressful evening getting a Christmas tree for their apartment (Leonard struggled chopping it down, the tree slid off their car roof, Leonard passed out bringing it up three stories and once they got it in they found a rodent still living in the tree).

* BigDamnKiss: [[spoiler:Ramona kisses Sheldon in "The Long Distance Dissonance." Sheldon reacts by flying to Princeton to propose to Amy.]]

Leonard and Penny hold a second wedding to invite their family to, resulting in significantly antagonized family relationships. Howard also has to deal with the Air Force taking an interest in his gyroscope design, as well as starting a family with Bernadette. Sheldon and Amy take their relationship to the next level by moving in together, while Raj finds himself at a crossroads after his father cuts him off financially.

* TheBusCameBack: Ramona Nowitzki from season two's "[[Recap/TheBigBangTheoryS2E6TheCooperNowitzkiTheorem The Cooper-Nowitzki Theorem]]" returns, now a doctor, and still infatuated with Sheldon.

* LikeFatherLikeSon: Or daughter, in this case. It's mentioned that Penny and Wyatt share a similar fondness for alcohol.

* CallingTheOldManOut: Parodied. Raj is criticized by his father for being spoiled and relying on his money, rather than being self-sufficient. Raj decides to go cold turkey on his father's money and calls him up intending to chastise him for calling him spoiled. His father was just so happy to not have someone siphoning his money Raj didn't really get to make his point. "Dad, I'm trying to tell you off and you're ruining it with your ''joy'' and ''delight!''"

* CallingTheOldManOut: Parodied. Raj is criticized by his father for being spoiled and relying on his money, rather than being self-sufficient. Raj decides to go cold turkey on his fathers money and calls him up intending to chastise him for calling him spoiled. His father was just so happy to not have someone siphoning his money Raj didn't really get to make his point. "Dad, I'm trying to tell you off and you're ruining it with your ''joy'' and ''delight''!"

** The silly ComicBook/{{Aquaman}} costume Raj wore in the fourth season episode "Justice League Recombination" returns as a costume he wears while holding a sign advertising Stuarts comic book shop.