Contradiction with Exodus 20:4
This verse contradicts Exodus 30:27 by prohibiting the making of graven images or likenesses, while Exodus 30:27 involves the sanctification of objects, which some could argue implies their veneration.
Exodus 20:4: Thou shalt not make unto thee any graven image, or any likeness [of any thing] that [is] in heaven above, or that [is] in the earth beneath, or that [is] in the water under the earth:
Contradiction with Deuteronomy 12:32
This verse instructs not to add or take away from God's commandments, while Exodus 30's instructions about the anointing oil and altar could imply additional commandments and practices.
Deuteronomy 12:32: What thing soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it.