Goofs

Erol calls the grandfather by the wrong name when arguing with his father about Einstein, the atomic bomb, and destroying the technology. He says "Al would tell you the same thing". The grandfather's name is Sal, not Al.

When Erol refers to "Al" he is in fact referring to Albert Einstein and not his grandfather Sal.

When Erol opens his phone to read Marika's text immediately after receipt, it is in his phone's Outbox.

When Erol and Gabe are playing chess the board is set up wrong (the corner right square at the bottom should be white - "white-to-right"). Plus the move Erol suggests that might checkmate his father in three makes no sense at all, as "pawn 5 to pawn 3" can be neither a capture nor a legal pawn move.

When the grandfather is explaining to the son what he thinks happened to the boy's father, the grandfather makes a comment to the effect that he doesn't understand it all because he's not 'a specialist in quantum mechanics'. This movie deals with time travel and relativity, not quantum mechanics. Relativity deals with the large scale and quantum mechanics deals with the small scale. The reconciliation of the two has been the holy grail of physics, 'Unified Field Theory'. To object that one doesn't understand time travel because one is not a quantum mechanic is nonsensical. No physics professor would make that mistake.

It's a bit odd that Grace was using an overhead projector for her presentation. Most teaching establishments had ditched them by then and were using computers, projectors and PowerPoint.