Why does Gretchen wave to Donnie's Mom, Rose?
Similar to the previous connection, it’s believed that she feels some sense of déjà vu when she sees Rose.
We don’t know if Rose or Gretchen ever met in the Tangent Universe, but even so, she might feel some connection with her and Donnie’s family, in a similar déjà vu sense.
After the scene of Donnie and his family discussing the Philosophy of Time Travel, you see Donnie and a girl in overalls jumping on a trampoline. You see Gretchen wearing something extremely similar to this after the second crash of the jet engine where she waves to Donnie’s mother. This may be evidence of Gretchen and Donnie’s mom/family having met before.
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