Piccolo can destroy a house with telekinesis, but he can't lift the Dragonball that falls off the stone mount back up to him at the end scene of the movie.
Before turning into Ozaru, Goku had a belt which seemed a little tight. Yet when he transforms into Ozaru and then back into his normal self the belt is in perfect conditions without a stretch mark.
When Goku is in the Ozaru form, the robe is loose (not tucked in the belt). After Turning into Goku again the robe is tucked in the belt, with no time to see Goku tuck it in himself.
During the martial arts tournament, Chi Chi receives a cut to her lower right arm. In the temple when she fights the copy of herself, you see it again. But at the end of the film when Goku goes to see her, there is no sign of a cut or even a scar. This is strange due to there not very long between these events.
Just before the eclipse the moon can be seen in a (waxing) crescent state, while it had to be in a (waning) crescent state before getting to new moon.
at the end of the movie when Goku changes into the Giant Ape is factually wrong. Anyone who knows, reads, or watches anything Dragon Ball knows that Sayians can not change WITHOUT THEIR TAIL and seeing as how Goku has no tail then he could not Transform in the movie.
Piccolo evaporates an entire lake to find the Dragonball located at the bottom. Why are there undisturbed bushes at the bottom of this now dry lake?
The gang of heroes (Goku, Roshi, Bulma, and Yamcha) would not be able to survive for very long near an active volcano, as inhaling the toxic gas and fumes would suffocate them.
Despite the film building to a climax during a total solar eclipse, which requires a New Moon, the film constantly shows a Full Moon, which never changes phase over the weeks the film takes place.
Roshi could leap out of the hole whenever he wanted, but wastes precious hours in the hole telling a story when time was running short to find the Dragonballs.
In the opening credits Oozaru is seen wearing the same gi Goku later wears even though its 2000 years before Goku is even born.
Goku has superhuman strength, but Chi-Chi does not have any visible injuries or even bruising from being kicked in the face by him.
How does Mai know who Chi-Chi is so that she can steal her blood to form a disguise? They never met before, so how would she know she's a friend of Goku? And how did she get an identical set of clothes to masquerade as Chi-Chi to steal the Dragonballs?
Piccolo is implied to be able to sense the location of Dragonballs, so then why did he attack Goku's house when it was no longer there? Wouldn't he be able to sense that Goku was carrying it with him?
Why did Yamcha wait until the last minute during the final confrontation with Piccolo to reveal that his car can actually fly?
The bullies threaten Goku by describing his potential beating as a massacre. A massacre, by definition, is the murder of several people in one event. Even if they had killed Goku, it still wouldn't be a massacre.
When Goku finds his dying grandpa under the rubble of their destroyed home, he tells him that Lord Piccolo has returned for the 7 Dragonballs. When Bulma arrives at his destroyed home searching for the Dragonballs, he asks if she's Piccolo, despite grandpa Gohan clearly referring to him by male pronouns.
Bulma breaks into Master Roshi's home to find his Dragonball, and Goku initially protests that this is breaking and entering, with Bulma arguing that it's not because his doors are unlocked. This justification would not hold up in a court of law.
Bulma saw that Mai was the thief that broke into her lab to steal the Dragonball, so why did she assume that Goku stole her Dragonball when first meeting him at the rubble of what used to be his house?