1. The mother's name is actually revealed in season one.
2. In the episode, "Disaster Averted," Marshall uses some slaps on Barney, saying he'll save the last of them "for a rainy day." In "End of the Aisle," when he uses his final slap on Barney, it's raining.
3. This scene hinted at Robin and Ted's breakup 12 episodes before it happened.
4. In the episode where Marshall's father dies, there is a countdown to his death throughout the episode, with numbers in scenes going down from 50 to one when Lily gets out of the cab to reveal the news.
5. When Barney tells Ted that he'll be with Robin until she's 40 and he can "have her after that," he essentially predicted what ends up happening.
6. When Ted is dating Cindy, he announces that his ideal woman is someone who can play guitar. When he meets the mother, she too is a talented guitarist.
7. In the scene where Robin tells Ted that timing is a bitch, "La Vie En Rose" is played in the background. Then, years later, Ted hears Tracy's voice for the first time when she's singing the same song.
8. In the scene where Ted and Tracy first meet at the Farhampton Train Station, the song playing in the background is "The Funeral" by Band of Horses.
9. In the episode "Milk," we find out that Ted's favourite book is Love in the Time of Cholera, which is about a man and woman who fall in love but can't be together. Later in life, the woman's husband dies and they end up together. Sound familiar?
10. And he also just so happens to be reading this book right before he meets Tracy for the first time.
11. When Ted is telling the story about Robin's mom not coming to her wedding, Tracy says: "What mother is going to miss her daughter's wedding?" Ted then chokes up. We later find out that the mother was already sick at that point.
12. The gut-wrenching Time Travellers episode.
13. That episode also ends with Bob Dylan's "If You See Her, Say Hello" playing in the background – a song about losing the one you love.
14. In this scene from season two, Barney has a baby and Ted and Robin are together. This is exactly what comes to pass at the end of the show.
15. This perfect foreshadowing and callback.
16. Ted and Tracy's shared love of coins ends up becoming the reason for naming their daughter "Penny."
17. This gravestone in season seven foreshadows the show's eventual ending.
18. And, finally, this line comes heartbreakingly true.
Some submissions have been edited for length and/or clarity.