Cordelia says in The Ring, “You’d think people’d get enough gratuitous violence watching Jerry Springer”. The Jerry Springer Show was famous for it’s fights between guests.

When Angel is fighting Trepkos his wounds, including the prominent stab wound in his chest change places, and even vanish throughout the fight.

When Angel is leaving the building where the fights took place in The Ring, there is no blood visible under his jacket from where Trepkos stabbed him with the wooden pole.

Both the Angel episode The Ring and The X-Files episode “Firewalker” featured a character named Daniel Trepkos - both were written by Howard Gordon.

The following scene was cut from The Ring:

Wesley: “All I’m saying is you might have thought of the horsehair sooner, not that being flung across a room isn’t jolly good exercise”.
Cordy: “Speaking of horsehair, where did you find that jacket?”
Guard: “Mr & Mrs Winslow, good to see you again.”
Wesley: “Don’t …

In Eternity, how can Angel jump through the window into Rebecca’s apartment to save her from the intruder? He was never invited in.

In Eternity, Angel says about Cordy’s play, “I’ve been to Hell but that was so much worse”. He’s referring to Becoming (Part 2), in which Buffy sent him to hell to save the world.

The following lines discussing Cordelia’s role in A Doll’s House were cut for length from Eternity:

Wesley: “I’ve always regarded Nora as one of the seminal characters of late-nineteenth, early-twentieth century literature”
Cordy: “Yeah, but I thought I managed to breathe a little life into her, anyway. You have to …

In the Angel episode, Eternity, we see Cordelia acting her way (badly) through Henrik Ibsen’s play A Doll’s House. The play is a critical look at Victorian marriages, concentrating on the decline of the marriage of Nora to Torvald. Cordelia plays Nora.

In Five By Five, when Faith is dancing and fighting, we hear “Living Dead Girl (Subliminal Seduction Mix)” by Rob Zombie.

In many episodes Cordelia’s apartment number was 212 and she had a porch outside her door, but in Five By Five, her apartment number is 6, she has neighbours and her door is inside.

The Angel episode Five By Five followed the Buffy episode Who Are You? In Five By Five, Lee Mercer calls Faith a, “busy little beaver”. In Who Are You?, Faith in Buffy’s body called herself a “busy little beaver”.

The following line of Angel’s was cut from Five By Five due to length:
“I seem to remember trying with Faith once….I had her in a safe place, on the verge of facing herself and what she’d done. Then her watcher knocked me unconscious with a tire iron, took her …

When Wesley is throwing darts in the bar in Sanctuary, the dartboard is black and white, but when he goes to take the darts out of the board, the dartboard is coloured.

Sanctuary was the last episode in which Sarah Michelle Gellar appeared in Angel. The character of Buffy appeared in the season five episode The Girl In Question but it was just a blonde head we saw and it not Sarah.
At the end of the episode, Wesley asks Angel is …