Goofs

In episode 2 Henry (8) and Henry (33) are in the museum drinking drinks and eating Barnums animal crackers. Their packaging hadn't changed in over a century. In august 2021 they changed it so the animals are no longer in cages, so when they meet in 1988, it should've been the old packaging when the animals were in cages.

Henry's mother uses a cell phone in 1988 when they weren't in common use until the nineties. Flip phones, like the one she was using, didn't exist until the 21st century.

At 4:57 in the episode, at the scene of the accident when Henry is 8, a list of versions (ages) of Henry present is listed on the screen -- 23 is listed twice.

There's no goof in this though since there is nothing to stop two versions of Henry being the same age as each other.

In the museum scene, it says it is 1988, and Henry's mum is still alive then. She uses a mobile flip phone in this scene, which is definitely an anachronism.