The third planet that the family tries turns out to be unacceptable because when the sun rises they discover it screams for the 42 hour day. However, they arrived via space, even if they couldn't hear it in space they would have been able to spot the permanently screaming sun as they approached. (They also would have been able to hear it, clearly the sound somehow travels through space anyway to end up audible in the planet's atmosphere, the same would be true in their vehicle).
Rick says Earth's TV signals take light-years to reach Birdperson's planet.
However, a light-year is a unit of distance, not time. As a scientist, Rick should know this and use the term correctly.
However, a light-year is a unit of distance, not time. As a scientist, Rick should know this and use the term correctly.
Around 00:25 Rick says "our TV signals take light years to reach his planet", light year is not a measurement unit for time, it is for measuring distance.
The planet which Rick and family finally decides to stay is too small to have a strong enough gravity to hold them to the surface, however it may have a higher mass which would account for the increased gravity in relation to it's size.