Demonic Spiders: Jetpack Thugs. They fly out of range of most of your weapons, and fire clusters of shots at you that are hard to dodge in numbers and do a lot of damage on the higher difficulties. The fact that a lot of bosses tend to summon them doesn't help.
"Funny Aneurysm" Moment: In-Universe. Early in the game, Talwyn (via hologram) fakes dying in space to try and amuse Ratchet. After Cronk and Zephyr are destroyed by Progs' detonator, she's not finding the subject of death so funny anymore...
Game-Breaker: As with its predecessors, the RYNO VII. It's powerful enough that, once it's fully upgraded, you won't need another weapon to defeat the final boss and the fight against it will only wind up being a few minutes long!
It's Short, So It Sucks!: Compared with some of the other Future games, Into the Nexus is pretty short, about twice the size of Quest for Booty. This game has the Nebulox 7 level, and only 5 planets in the game. One of them hosts the tournament, and the areas you visit on the other 4 will take only twice the time as they would be in a regular-length Ratchet & Clank game. That said, the developers said it would be shorter than most Ratchet & Clank games, and the game was budget-priced at the time of release, so there was at least fair warning that the game wouldn't exactly be a full-length title.
The Nethers and their leader "Mr. Eye" are extremely freaky in appearance. Which is fitting considering that they're Eldritch Abominations-especially the leader that resembles a huge Cyclopean angler fish with a lot of teeth.
When Clank descends into the Netherverse to rescue Vendra, it's very reminiscent of Limbo with Clank in silhouette and the generally creepy ambiance. Even more so in that Clank-during gameplay anyway-is always free-falling and must lead two vicious Nethers back to free Vendra from the barrier imprisoning her.
The orphanages where Vendra and her brother grew up deserves note as well. The outside is dominated by four cyclopian animatronics who constantly look like they are laughing madly, while happy music is playing. Once Ratchet steps inside, the nature of how the orphanage was run becomes noticeable. There are small metal baskets lying around and robotic claws are going along the ceiling, some still holding some of the baskets. Said claws follow a path that goes through some showers before ending at a conveyor belt which leads into the basement. The basement turns out to have been the windowless sleeping room for the children, with three giant hamster drinking stations.
Scrappy Mechanic: You can't customize your Quick Select at all; weapons are locked in the order you get them.
Tear Jerker: Talwyn's reactions to receiving the news about Cronk and Zephyr's deaths and begging Ratchet to come back as he and Clank are now all she has left.
The "For Cronk and Zephyr" Skill Point, which requires you to beat Neftin Prog without taking damage. Dodging his attacks on their own is relatively easy, but there's a catch. Actually two. Firstly Neftin has a severe case of Hitbox Dissonance, and you'll often find yourself randomly taking Collision Damage when you weren't touching him at all. Second, he summons Thugs later in the fight, including jetpack ones (see above), and dodging both them and him at the same time is incredibly hard.
The "Vandal" Skill Point, which requires breaking all of the windows on Planet Silox. Unlike the above, this one isn't too easy, but there's still a catch. Actually three. Firstly, you aren't actually told what the windows look like (they're very tall and sky blue). Secondly, a lot of these windows require looking around at every building and certain buildings only have a few windows that can be broken among a bunch of windows that do nothing. Additionally, some of the windows are permanently missable until Challenge Mode. However, there is one thing that's nice about this particular Skill Point, and it's that your broken window percentage will not be lost if you die.
Underused Game Mechanic: This game gives the Gravity Boots the ability to target and leap to different magnetic surfaces. You really only need to do this during the tutorial level and the final boss.